diff --git a/lib/YANLib/Nullable/YANDateTime.Nullable.cs b/lib/YANLib/Nullable/YANDateTime.Nullable.cs
index ad309cb..21fb36d 100644
--- a/lib/YANLib/Nullable/YANDateTime.Nullable.cs
+++ b/lib/YANLib/Nullable/YANDateTime.Nullable.cs
@@ -24,7 +24,7 @@ public static partial class YANDateTime
     /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format, and the specified default value for any strings that fail to convert.</returns>
     public static IEnumerable<DateTime?> ToDateTime(this IEnumerable<string> strs, string fmt, DateTime? dfltVal)
     {
-        if (strs.AllNullOrWhiteSpace())
+        if (strs.AllWhiteSpaceOrNull())
         {
             yield break;
         }
diff --git a/lib/YANLib/Nullable/YANDateTime.cs b/lib/YANLib/Nullable/YANDateTime.cs
index 6b78c6e..e1f49ca 100644
--- a/lib/YANLib/Nullable/YANDateTime.cs
+++ b/lib/YANLib/Nullable/YANDateTime.cs
@@ -25,7 +25,7 @@ public static partial class YANDateTime
     /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string.</returns>
     public static IEnumerable<DateTime?> ToDateTime(this IEnumerable<string> strs)
     {
-        if (strs.AllNullOrWhiteSpace())
+        if (strs.AllWhiteSpaceOrNull())
         {
             yield break;
         }
@@ -53,7 +53,7 @@ public static partial class YANDateTime
     /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format.</returns>
     public static IEnumerable<DateTime?> ToDateTime(this IEnumerable<string> strs, string fmt)
     {
-        if (strs.AllNullOrWhiteSpace())
+        if (strs.AllWhiteSpaceOrNull())
         {
             yield break;
         }
@@ -83,7 +83,7 @@ public static partial class YANDateTime
     /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format, and the specified default value for any strings that fail to convert.</returns>
     public static IEnumerable<DateTime?> ToDateTime(this IEnumerable<string> strs, string fmt, DateTime dfltVal)
     {
-        if (strs.AllNullOrWhiteSpace())
+        if (strs.AllWhiteSpaceOrNull())
         {
             yield break;
         }
diff --git a/lib/YANLib/Ultimate/YANDateTime.Nullable.cs b/lib/YANLib/Ultimate/YANDateTime.Nullable.cs
new file mode 100644
index 0000000..cd802d4
--- /dev/null
+++ b/lib/YANLib/Ultimate/YANDateTime.Nullable.cs
@@ -0,0 +1,210 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace YANLib.Ultimate;
+
+public static partial class YANDateTime
+{
+    /// <summary>
+    /// Converts a collection of string representations of dates and times to their <see cref="DateTime"/> equivalents using the specified format.
+    /// Returns an enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format, and returns the specified default value for any strings that fail to convert.
+    /// </summary>
+    /// <param name="strs">The collection of strings to be converted to <see cref="DateTime"/>.</param>
+    /// <param name="fmt">The format of the input strings.</param>
+    /// <param name="dfltVal">The default value to return for any strings that fail to convert.</param>
+    /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format, and the specified default value for any strings that fail to convert.</returns>
+    public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs, string fmt, DateTime? dfltVal)
+    {
+        if (strs.AllWhiteSpaceOrNull())
+        {
+            yield break;
+        }
+        foreach (var str in strs)
+        {
+            yield return str.ToDateTime(fmt, dfltVal);
+        }
+    }
+
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime? max, T size) where T : struct
+    {
+        for (var i = 0ul; i < size.ToUlong(); i++)
+        {
+            yield return YANLib.YANDateTime.GenerateRandomDateTime(min, max);
+        }
+    }
+
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime? max, T? size) where T : struct
+    {
+        for (var i = 0ul; i < size.ToUlong(); i++)
+        {
+            yield return YANLib.YANDateTime.GenerateRandomDateTime(min, max);
+        }
+    }
+
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime min, DateTime? max, T size) where T : struct
+    {
+        for (var i = 0ul; i < size.ToUlong(); i++)
+        {
+            yield return YANLib.YANDateTime.GenerateRandomDateTime(min, max);
+        }
+    }
+
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime min, DateTime? max, T? size) where T : struct
+    {
+        for (var i = 0ul; i < size.ToUlong(); i++)
+        {
+            yield return YANLib.YANDateTime.GenerateRandomDateTime(min, max);
+        }
+    }
+
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime max, T size) where T : struct
+    {
+        for (var i = 0ul; i < size.ToUlong(); i++)
+        {
+            yield return YANLib.YANDateTime.GenerateRandomDateTime(min, max);
+        }
+    }
+
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime max, T? size) where T : struct
+    {
+        for (var i = 0ul; i < size.ToUlong(); i++)
+        {
+            yield return YANLib.YANDateTime.GenerateRandomDateTime(min, max);
+        }
+    }
+
+    public static IEnumerable<int> GetWeekOfYear(this IEnumerable<DateTime?> dts)
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.GetWeekOfYear();
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1 tzSrc, T2 tzDst) where T1 : struct where T2 : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzSrc, tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzSrc, tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzSrc, tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzSrc, tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzSrc, tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzSrc, tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzSrc, tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T>(this IEnumerable<DateTime?> dts, T tzDst) where T : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T>(this IEnumerable<DateTime> dts, T? tzDst) where T : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T>(this IEnumerable<DateTime?> dts, T? tzDst) where T : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzDst);
+        }
+    }
+}
diff --git a/lib/YANLib/Ultimate/YANDateTime.cs b/lib/YANLib/Ultimate/YANDateTime.cs
new file mode 100644
index 0000000..e215dd0
--- /dev/null
+++ b/lib/YANLib/Ultimate/YANDateTime.cs
@@ -0,0 +1,105 @@
+namespace YANLib.Ultimate;
+
+public static partial class YANDateTime
+{
+    /// <summary>
+    /// Converts a collection of string representations of dates and times to their <see cref="DateTime"/> equivalents.
+    /// Returns an enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string, and skips any strings that fail to convert.
+    /// </summary>
+    /// <param name="strs">The collection of strings to be converted to <see cref="DateTime"/>.</param>
+    /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string.</returns>
+    public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs)
+    {
+        if (strs.AllWhiteSpaceOrNull())
+        {
+            yield break;
+        }
+        foreach (var str in strs)
+        {
+            yield return str.ToDateTime();
+        }
+    }
+
+    /// <summary>
+    /// Converts a collection of string representations of dates and times to their <see cref="DateTime"/> equivalents using the specified format.
+    /// Returns an enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format, and skips any strings that fail to convert.
+    /// </summary>
+    /// <param name="strs">The collection of strings to be converted to <see cref="DateTime"/>.</param>
+    /// <param name="fmt">The format of the input strings.</param>
+    /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format.</returns>
+    public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs, string fmt)
+    {
+        if (strs.AllWhiteSpaceOrNull())
+        {
+            yield break;
+        }
+        foreach (var str in strs)
+        {
+            yield return str.ToDateTime(fmt);
+        }
+    }
+
+    /// <summary>
+    /// Converts a collection of string representations of dates and times to their <see cref="DateTime"/> equivalents using the specified format.
+    /// Returns an enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format, and returns the specified default value for any strings that fail to convert.
+    /// </summary>
+    /// <param name="strs">The collection of strings to be converted to <see cref="DateTime"/>.</param>
+    /// <param name="fmt">The format of the input strings.</param>
+    /// <param name="dfltVal">The default value to return for any strings that fail to convert.</param>
+    /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format, and the specified default value for any strings that fail to convert.</returns>
+    public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs, string fmt, DateTime dfltVal)
+    {
+        if (strs.AllWhiteSpaceOrNull())
+        {
+            yield break;
+        }
+        foreach (var str in strs)
+        {
+            yield return str.ToDateTime(fmt, dfltVal);
+        }
+    }
+
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime min, DateTime max, T size) where T : struct
+    {
+        for (var i = 0ul; i < size.ToUlong(); i++)
+        {
+            yield return YANLib.YANDateTime.GenerateRandomDateTime(min, max);
+        }
+    }
+
+    public static IEnumerable<int> GetWeekOfYear(this IEnumerable<DateTime> dts)
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.GetWeekOfYear();
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1 tzSrc, T2 tzDst) where T1 : struct where T2 : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzSrc, tzDst);
+        }
+    }
+
+    public static IEnumerable<DateTime> ChangeTimeZone<T>(this IEnumerable<DateTime> dts, T tzDst) where T : struct
+    {
+        if (dts is null || !dts.Any())
+        {
+            yield break;
+        }
+        foreach (var dt in dts)
+        {
+            yield return dt.ChangeTimeZone(tzDst);
+        }
+    }
+}
diff --git a/lib/YANLib/YANDateTime.Nullable.cs b/lib/YANLib/YANDateTime.Nullable.cs
index ee22aca..6869ab9 100644
--- a/lib/YANLib/YANDateTime.Nullable.cs
+++ b/lib/YANLib/YANDateTime.Nullable.cs
@@ -1,4 +1,6 @@
-using static System.DateTime;
+using System.Linq;
+using static System.DateTime;
+using static System.Linq.Enumerable;
 
 namespace YANLib;
 
@@ -22,17 +24,7 @@ public static partial class YANDateTime
     /// <param name="fmt">The format of the input strings.</param>
     /// <param name="dfltVal">The default value to return for any strings that fail to convert.</param>
     /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format, and the specified default value for any strings that fail to convert.</returns>
-    public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs, string fmt, DateTime? dfltVal)
-    {
-        if (strs.AllNullOrWhiteSpace())
-        {
-            yield break;
-        }
-        foreach (var str in strs)
-        {
-            yield return str.ToDateTime(fmt, dfltVal);
-        }
-    }
+    public static IEnumerable<DateTime>? ToDateTime(this IEnumerable<string> strs, string fmt, DateTime? dfltVal) => strs.AllWhiteSpaceOrNull() ? default : strs.Select(s => s.ToDateTime(fmt, dfltVal));
 
     /// <summary>
     /// Generates a random <see cref="DateTime"/> object between the specified minimum and maximum values.
@@ -65,67 +57,21 @@ public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs, st
     /// <returns>A randomly generated <see cref="DateTime"/> object between the minimum <see cref="DateTime"/> value and the specified maximum value.</returns>
     public static DateTime GenerateRandomDateTime(DateTime? max) => max.HasValue ? GenerateRandomDateTime(max.Value) : default;
 
-    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime? max, T size) where T : struct
-    {
-        for (var i = 0ul; i < size.ToUlong(); i++)
-        {
-            yield return GenerateRandomDateTime(min, max);
-        }
-    }
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime? max, T size) where T : struct => Range(0, size.ToUint().ToInt()).Select(i => GenerateRandomDateTime(min, max));
 
-    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime? max, T? size) where T : struct
-    {
-        for (var i = 0ul; i < size.ToUlong(); i++)
-        {
-            yield return GenerateRandomDateTime(min, max);
-        }
-    }
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime? max, T? size) where T : struct => Range(0, size.ToUint().ToInt()).Select(i => GenerateRandomDateTime(min, max));
 
-    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime min, DateTime? max, T size) where T : struct
-    {
-        for (var i = 0ul; i < size.ToUlong(); i++)
-        {
-            yield return GenerateRandomDateTime(min, max);
-        }
-    }
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime min, DateTime? max, T size) where T : struct => Range(0, size.ToUint().ToInt()).Select(i => GenerateRandomDateTime(min, max));
 
-    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime min, DateTime? max, T? size) where T : struct
-    {
-        for (var i = 0ul; i < size.ToUlong(); i++)
-        {
-            yield return GenerateRandomDateTime(min, max);
-        }
-    }
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime min, DateTime? max, T? size) where T : struct => Range(0, size.ToUint().ToInt()).Select(i => GenerateRandomDateTime(min, max));
 
-    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime max, T size) where T : struct
-    {
-        for (var i = 0ul; i < size.ToUlong(); i++)
-        {
-            yield return GenerateRandomDateTime(min, max);
-        }
-    }
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime max, T size) where T : struct => Range(0, size.ToUint().ToInt()).Select(i => GenerateRandomDateTime(min, max));
 
-    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime max, T? size) where T : struct
-    {
-        for (var i = 0ul; i < size.ToUlong(); i++)
-        {
-            yield return GenerateRandomDateTime(min, max);
-        }
-    }
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime? min, DateTime max, T? size) where T : struct => Range(0, size.ToUint().ToInt()).Select(i => GenerateRandomDateTime(min, max));
 
     public static int GetWeekOfYear(this DateTime? dt) => dt.HasValue ? dt.Value.GetWeekOfYear() : default;
 
-    public static IEnumerable<int> GetWeekOfYear(this IEnumerable<DateTime?> dts)
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.GetWeekOfYear();
-        }
-    }
+    public static IEnumerable<int>? GetWeekOfYear(this IEnumerable<DateTime?> dts) => dts is null || !dts.Any() ? default : dts.Select(d => d.GetWeekOfYear());
 
     public static int TotalMonths(DateTime? dt1, DateTime dt2) => dt1.HasValue ? TotalMonths(dt1.Value, dt2) : default;
 
@@ -135,17 +81,7 @@ public static IEnumerable<int> GetWeekOfYear(this IEnumerable<DateTime?> dts)
 
     public static DateTime ChangeTimeZone<T1, T2>(this DateTime? dt, T1 tzSrc, T2 tzDst) where T1 : struct where T2 : struct => dt.HasValue ? dt.Value.ChangeTimeZone(tzSrc, tzDst) : default;
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1 tzSrc, T2 tzDst) where T1 : struct where T2 : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzSrc, tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1 tzSrc, T2 tzDst) where T1 : struct where T2 : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzSrc, tzDst));
 
     public static void ChangeTimeZone<T1, T2>(this IList<DateTime?> dts, T1 tzSrc, T2 tzDst) where T1 : struct where T2 : struct
     {
@@ -160,17 +96,7 @@ public static void ChangeTimeZone<T1, T2>(this IList<DateTime?> dts, T1 tzSrc, T
 
     public static DateTime ChangeTimeZone<T1, T2>(this DateTime dt, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct => tzSrc.HasValue ? dt.ChangeTimeZone(tzSrc.Value, tzDst) : dt.ChangeTimeZone(tzDst);
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzSrc, tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzSrc, tzDst));
 
     public static void ChangeTimeZone<T1, T2>(this IList<DateTime> dts, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct
     {
@@ -185,17 +111,7 @@ public static void ChangeTimeZone<T1, T2>(this IList<DateTime> dts, T1? tzSrc, T
 
     public static DateTime ChangeTimeZone<T1, T2>(this DateTime dt, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct => tzDst.HasValue ? dt.ChangeTimeZone(tzSrc, tzDst.Value) : dt;
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzSrc, tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzSrc, tzDst));
 
     public static void ChangeTimeZone<T1, T2>(this IList<DateTime> dts, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct
     {
@@ -210,17 +126,7 @@ public static void ChangeTimeZone<T1, T2>(this IList<DateTime> dts, T1 tzSrc, T2
 
     public static DateTime ChangeTimeZone<T1, T2>(this DateTime? dt, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct => dt.HasValue ? dt.Value.ChangeTimeZone(tzSrc, tzDst) : default;
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzSrc, tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzSrc, tzDst));
 
     public static void ChangeTimeZone<T1, T2>(this IList<DateTime?> dts, T1? tzSrc, T2 tzDst) where T1 : struct where T2 : struct
     {
@@ -235,17 +141,7 @@ public static void ChangeTimeZone<T1, T2>(this IList<DateTime?> dts, T1? tzSrc,
 
     public static DateTime ChangeTimeZone<T1, T2>(this DateTime? dt, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct => dt.HasValue ? dt.Value.ChangeTimeZone(tzSrc, tzDst) : default;
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzSrc, tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzSrc, tzDst));
 
     public static void ChangeTimeZone<T1, T2>(this IList<DateTime?> dts, T1 tzSrc, T2? tzDst) where T1 : struct where T2 : struct
     {
@@ -260,17 +156,7 @@ public static void ChangeTimeZone<T1, T2>(this IList<DateTime?> dts, T1 tzSrc, T
 
     public static DateTime ChangeTimeZone<T1, T2>(this DateTime dt, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct => tzSrc.HasValue ? dt.ChangeTimeZone(tzSrc.Value, tzDst) : dt.ChangeTimeZone(tzDst);
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzSrc, tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzSrc, tzDst));
 
     public static void ChangeTimeZone<T1, T2>(this IList<DateTime> dts, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct
     {
@@ -285,17 +171,7 @@ public static void ChangeTimeZone<T1, T2>(this IList<DateTime> dts, T1? tzSrc, T
 
     public static DateTime ChangeTimeZone<T1, T2>(this DateTime? dt, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct => dt.HasValue ? dt.Value.ChangeTimeZone(tzSrc, tzDst) : default;
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzSrc, tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T1, T2>(this IEnumerable<DateTime?> dts, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzSrc, tzDst));
 
     public static void ChangeTimeZone<T1, T2>(this IList<DateTime?> dts, T1? tzSrc, T2? tzDst) where T1 : struct where T2 : struct
     {
@@ -310,17 +186,7 @@ public static void ChangeTimeZone<T1, T2>(this IList<DateTime?> dts, T1? tzSrc,
 
     public static DateTime ChangeTimeZone<T>(this DateTime? dt, T tzDst) where T : struct => dt.ChangeTimeZone(0, tzDst);
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T>(this IEnumerable<DateTime?> dts, T tzDst) where T : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T>(this IEnumerable<DateTime?> dts, T tzDst) where T : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzDst));
 
     public static void ChangeTimeZone<T>(this IList<DateTime?> dts, T tzDst) where T : struct
     {
@@ -335,17 +201,7 @@ public static void ChangeTimeZone<T>(this IList<DateTime?> dts, T tzDst) where T
 
     public static DateTime ChangeTimeZone<T>(this DateTime dt, T? tzDst) where T : struct => dt.ChangeTimeZone(0, tzDst);
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T>(this IEnumerable<DateTime> dts, T? tzDst) where T : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T>(this IEnumerable<DateTime> dts, T? tzDst) where T : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzDst));
 
     public static void ChangeTimeZone<T>(this IList<DateTime> dts, T? tzDst) where T : struct
     {
@@ -360,17 +216,7 @@ public static void ChangeTimeZone<T>(this IList<DateTime> dts, T? tzDst) where T
 
     public static DateTime ChangeTimeZone<T>(this DateTime? dt, T? tzDst) where T : struct => dt.ChangeTimeZone(0, tzDst);
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T>(this IEnumerable<DateTime?> dts, T? tzDst) where T : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T>(this IEnumerable<DateTime?> dts, T? tzDst) where T : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzDst));
 
     public static void ChangeTimeZone<T>(this IList<DateTime?> dts, T? tzDst) where T : struct
     {
diff --git a/lib/YANLib/YANDateTime.cs b/lib/YANLib/YANDateTime.cs
index 9c17504..f8bb3eb 100644
--- a/lib/YANLib/YANDateTime.cs
+++ b/lib/YANLib/YANDateTime.cs
@@ -2,6 +2,7 @@
 using static System.Globalization.CultureInfo;
 using static System.Globalization.DateTimeFormatInfo;
 using static System.Globalization.DateTimeStyles;
+using static System.Linq.Enumerable;
 using static System.Math;
 using static YANLib.YANNum;
 
@@ -23,17 +24,7 @@ public static partial class YANDateTime
     /// </summary>
     /// <param name="strs">The collection of strings to be converted to <see cref="DateTime"/>.</param>
     /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string.</returns>
-    public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs)
-    {
-        if (strs.AllNullOrWhiteSpace())
-        {
-            yield break;
-        }
-        foreach (var str in strs)
-        {
-            yield return str.ToDateTime();
-        }
-    }
+    public static IEnumerable<DateTime>? ToDateTime(this IEnumerable<string> strs) => strs.AllWhiteSpaceOrNull() ? default : strs.Select(s => s.ToDateTime());
 
     /// <summary>
     /// Converts the specified string representation of a date and time to its <see cref="DateTime"/> equivalent using the specified format.
@@ -51,17 +42,7 @@ public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs)
     /// <param name="strs">The collection of strings to be converted to <see cref="DateTime"/>.</param>
     /// <param name="fmt">The format of the input strings.</param>
     /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format.</returns>
-    public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs, string fmt)
-    {
-        if (strs.AllNullOrWhiteSpace())
-        {
-            yield break;
-        }
-        foreach (var str in strs)
-        {
-            yield return str.ToDateTime(fmt);
-        }
-    }
+    public static IEnumerable<DateTime>? ToDateTime(this IEnumerable<string> strs, string fmt) => strs.AllWhiteSpaceOrNull() ? default : strs.Select(s => s.ToDateTime(fmt));
 
     /// <summary>
     /// Converts the specified string representation of a date and time to its <see cref="DateTime"/> equivalent using the specified format.
@@ -81,17 +62,7 @@ public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs, st
     /// <param name="fmt">The format of the input strings.</param>
     /// <param name="dfltVal">The default value to return for any strings that fail to convert.</param>
     /// <returns>An enumerable collection of <see cref="DateTime"/> objects for each successfully converted input string in the specified format, and the specified default value for any strings that fail to convert.</returns>
-    public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs, string fmt, DateTime dfltVal)
-    {
-        if (strs.AllNullOrWhiteSpace())
-        {
-            yield break;
-        }
-        foreach (var str in strs)
-        {
-            yield return str.ToDateTime(fmt, dfltVal);
-        }
-    }
+    public static IEnumerable<DateTime>? ToDateTime(this IEnumerable<string> strs, string fmt, DateTime dfltVal) => strs.AllWhiteSpaceOrNull() ? default : strs.Select(s => s.ToDateTime(fmt, dfltVal));
 
     /// <summary>
     /// Generates a random <see cref="DateTime"/> object between the specified minimum and maximum values.
@@ -114,27 +85,11 @@ public static IEnumerable<DateTime> ToDateTime(this IEnumerable<string> strs, st
     /// <returns>A randomly generated <see cref="DateTime"/> object between the minimum <see cref="DateTime"/> value and the specified maximum value.</returns>
     public static DateTime GenerateRandomDateTime(DateTime max) => GenerateRandomDateTime(max > Today ? Today : MinValue, max);
 
-    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime min, DateTime max, T size) where T : struct
-    {
-        for (var i = 0ul; i < size.ToUlong(); i++)
-        {
-            yield return GenerateRandomDateTime(min, max);
-        }
-    }
+    public static IEnumerable<DateTime> GenerateRandomDateTimes<T>(DateTime min, DateTime max, T size) where T : struct => Range(0, size.ToUint().ToInt()).Select(i => GenerateRandomDateTime(min, max));
 
     public static int GetWeekOfYear(this DateTime dt) => CurrentInfo.Calendar.GetWeekOfYear(dt, CurrentInfo.CalendarWeekRule, CurrentInfo.FirstDayOfWeek);
 
-    public static IEnumerable<int> GetWeekOfYear(this IEnumerable<DateTime> dts)
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.GetWeekOfYear();
-        }
-    }
+    public static IEnumerable<int>? GetWeekOfYear(this IEnumerable<DateTime> dts) => dts is null || !dts.Any() ? default : dts.Select(d => d.GetWeekOfYear());
 
     public static int TotalMonths(DateTime dt1, DateTime dt2) => Abs((dt1.Year - dt2.Year) * 12 + dt1.Month - dt2.Month);
 
@@ -149,17 +104,7 @@ public static DateTime ChangeTimeZone<T1, T2>(this DateTime dt, T1 tzSrc, T2 tzD
         };
     }
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1 tzSrc, T2 tzDst) where T1 : struct where T2 : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzSrc, tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T1, T2>(this IEnumerable<DateTime> dts, T1 tzSrc, T2 tzDst) where T1 : struct where T2 : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzSrc, tzDst));
 
     public static void ChangeTimeZone<T1, T2>(this IList<DateTime> dts, T1 tzSrc, T2 tzDst) where T1 : struct where T2 : struct
     {
@@ -174,17 +119,7 @@ public static void ChangeTimeZone<T1, T2>(this IList<DateTime> dts, T1 tzSrc, T2
 
     public static DateTime ChangeTimeZone<T>(this DateTime dt, T tzDst) where T : struct => dt.ChangeTimeZone(0, tzDst);
 
-    public static IEnumerable<DateTime> ChangeTimeZone<T>(this IEnumerable<DateTime> dts, T tzDst) where T : struct
-    {
-        if (dts is null || !dts.Any())
-        {
-            yield break;
-        }
-        foreach (var dt in dts)
-        {
-            yield return dt.ChangeTimeZone(tzDst);
-        }
-    }
+    public static IEnumerable<DateTime>? ChangeTimeZone<T>(this IEnumerable<DateTime> dts, T tzDst) where T : struct => dts is null || !dts.Any() ? default : dts.Select(d => d.ChangeTimeZone(tzDst));
 
     public static void ChangeTimeZone<T>(this IList<DateTime> dts, T tzDst) where T : struct
     {
diff --git a/lib/YANLib/YANEnumerable.cs b/lib/YANLib/YANEnumerable.cs
index e5a0650..6448549 100644
--- a/lib/YANLib/YANEnumerable.cs
+++ b/lib/YANLib/YANEnumerable.cs
@@ -10,7 +10,7 @@ public static partial class YANEnumerable
     public static IEnumerable<List<T>> ChunkBySize<T, T1>(this List<T> srcs, T1 chunkSize) where T1 : struct
     {
         var size = chunkSize.ToInt();
-        if (srcs.IsNullOrEmpty() && size < 1)
+        if (srcs.IsEmptyOrNull() && size < 1)
         {
             yield break;
         }
@@ -23,7 +23,7 @@ public static IEnumerable<List<T>> ChunkBySize<T, T1>(this List<T> srcs, T1 chun
 
     public static IEnumerable<T> Clean<T>(this IEnumerable<T> srcs)
     {
-        if (srcs.IsNullOrEmpty())
+        if (srcs.IsEmptyOrNull())
         {
             yield break;
         }
@@ -49,7 +49,7 @@ public static IEnumerable<T> Clean<T>(this IEnumerable<T> srcs)
 
     public static void Clean<T>(this ICollection<T> srcs)
     {
-        if (srcs.IsNotNullAndEmpty())
+        if (srcs.IsNotEmptyAndNull())
         {
             var t = typeof(T);
             if (t.IsClass || GetUnderlyingType(t) is not null)
@@ -73,7 +73,7 @@ public static IEnumerable<string> Clean(this IEnumerable<string> srcs)
         }
         foreach (var src in srcs)
         {
-            if (src.IsNotNullAndWhiteSpace())
+            if (src.IsNotWhiteSpaceAndNull())
             {
                 yield return src;
             }
@@ -86,7 +86,7 @@ public static void Clean(this ICollection<string> srcs)
         {
             foreach (var src in srcs)
             {
-                if (src.IsNullOrWhiteSpace())
+                if (src.IsWhiteSpaceOrNull())
                 {
                     _ = srcs.Remove(src);
                 }
@@ -94,19 +94,19 @@ public static void Clean(this ICollection<string> srcs)
         }
     }
 
-    public static bool IsNullOrEmpty<T>(this IEnumerable<T> srcs) => srcs is null || !srcs.Any();
+    public static bool IsEmptyOrNull<T>(this IEnumerable<T> srcs) => srcs is null || !srcs.Any();
 
-    public static bool IsNullOrEmpty<T>(this IReadOnlyCollection<T> srcs) => srcs is null || srcs.Count < 1;
+    public static bool IsEmptyOrNull<T>(this ICollection<T> srcs) => srcs is null || srcs.Count < 1;
 
-    public static bool IsNotNullAndEmpty<T>(this IEnumerable<T> srcs) => srcs is not null && srcs.Any();
+    public static bool IsNotEmptyAndNull<T>(this IEnumerable<T> srcs) => srcs is not null && srcs.Any();
 
-    public static bool IsNotNullAndEmpty<T>(this IReadOnlyCollection<T> srcs) => srcs is not null && srcs.Count > 0;
+    public static bool IsNotEmptyAndNull<T>(this ICollection<T> srcs) => srcs is not null && srcs.Count > 0;
 
-    public static bool AllNullOrEmpty<T>(IEnumerable<T?> srcs) where T : class => !srcs.Any(x => x is not null || x.AnyPropertiesNotDefault());
+    public static bool AllEmptyOrNull<T>(this IEnumerable<T?> srcs) where T : class => !srcs.Any(x => x is not null || x.AnyPropertiesNotDefault());
 
-    public static bool AnyNullOrEmpty<T>(IEnumerable<T?> srcs) where T : class => srcs.Any(x => x is null || x.AllPropertiesDefault());
+    public static bool AnyEmptyOrNull<T>(this IEnumerable<T?> srcs) where T : class => srcs.Any(x => x is null || x.AllPropertiesDefault());
 
-    public static bool AllNotNullAndEmpty<T>(IEnumerable<T?> srcs) where T : class => !srcs.Any(x => x is null || x.AllPropertiesDefault());
+    public static bool AllNotEmptyAndNull<T>(this IEnumerable<T?> srcs) where T : class => !srcs.Any(x => x is null || x.AllPropertiesDefault());
 
-    public static bool AnyNotNullAndEmpty<T>(IEnumerable<T?> srcs) where T : class => srcs.Any(x => x is not null || x.AnyPropertiesNotDefault());
+    public static bool AnyNotEmptyAndNull<T>(this IEnumerable<T?> srcs) where T : class => srcs.Any(x => x is not null || x.AnyPropertiesNotDefault());
 }
diff --git a/lib/YANLib/YANModel.Property.cs b/lib/YANLib/YANModel.Property.cs
index 4666fa3..27bfdd7 100644
--- a/lib/YANLib/YANModel.Property.cs
+++ b/lib/YANLib/YANModel.Property.cs
@@ -23,7 +23,7 @@ public static bool AllPropertiesNotDefault<T>(this T? mdl) where T : class
         return true;
     }
 
-    public static bool AllPropertiesNotDefault<T>(this IEnumerable<T?> mdls) where T : class => mdls.IsNotNullAndEmpty() && !mdls.Any(x => x.AnyPropertiesDefault());
+    public static bool AllPropertiesNotDefault<T>(this IEnumerable<T?> mdls) where T : class => mdls.IsNotEmptyAndNull() && !mdls.Any(x => x.AnyPropertiesDefault());
 
     public static bool AllPropertiesDefault<T>(this T? mdl) where T : class
     {
@@ -42,7 +42,7 @@ public static bool AllPropertiesDefault<T>(this T? mdl) where T : class
         return true;
     }
 
-    public static bool AllPropertiesDefault<T>(this IEnumerable<T?> mdls) where T : class => mdls.IsNotNullAndEmpty() && !mdls.Any(x => x.AnyPropertiesNotDefault());
+    public static bool AllPropertiesDefault<T>(this IEnumerable<T?> mdls) where T : class => mdls.IsNotEmptyAndNull() && !mdls.Any(x => x.AnyPropertiesNotDefault());
 
     public static bool AnyPropertiesNotDefault<T>(this T? mdl) where T : class
     {
@@ -61,7 +61,7 @@ public static bool AnyPropertiesNotDefault<T>(this T? mdl) where T : class
         return false;
     }
 
-    public static bool AnyPropertiesNotDefault<T>(this IEnumerable<T?> mdls) where T : class => mdls.IsNotNullAndEmpty() && mdls.Any(x => x.AnyPropertiesNotDefault());
+    public static bool AnyPropertiesNotDefault<T>(this IEnumerable<T?> mdls) where T : class => mdls.IsNotEmptyAndNull() && mdls.Any(x => x.AnyPropertiesNotDefault());
 
     public static bool AnyPropertiesDefault<T>(this T? mdl) where T : class
     {
@@ -80,11 +80,11 @@ public static bool AnyPropertiesDefault<T>(this T? mdl) where T : class
         return false;
     }
 
-    public static bool AnyPropertiesDefault<T>(this IEnumerable<T?> mdls) where T : class => mdls.IsNotNullAndEmpty() && mdls.Any(x => x.AnyPropertiesDefault());
+    public static bool AnyPropertiesDefault<T>(this IEnumerable<T?> mdls) where T : class => mdls.IsNotEmptyAndNull() && mdls.Any(x => x.AnyPropertiesDefault());
 
     public static bool AllPropertiesNotDefault<T>(this T? mdl, params string[] names) where T : class
     {
-        if (mdl is null || names.AllNullOrWhiteSpace())
+        if (mdl is null || names.AllWhiteSpaceOrNull())
         {
             return false;
         }
@@ -99,11 +99,11 @@ public static bool AllPropertiesNotDefault<T>(this T? mdl, params string[] names
         return true;
     }
 
-    public static bool AllPropertiesNotDefault<T>(this IEnumerable<T?> mdls, params string[] names) where T : class => mdls.IsNotNullAndEmpty() && !mdls.Any(x => x.AnyPropertiesDefault(names));
+    public static bool AllPropertiesNotDefault<T>(this IEnumerable<T?> mdls, params string[] names) where T : class => mdls.IsNotEmptyAndNull() && !mdls.Any(x => x.AnyPropertiesDefault(names));
 
     public static bool AllPropertiesDefault<T>(this T? mdl, params string[] names) where T : class
     {
-        if (mdl is null || names.AllNullOrWhiteSpace())
+        if (mdl is null || names.AllWhiteSpaceOrNull())
         {
             return false;
         }
@@ -118,11 +118,11 @@ public static bool AllPropertiesDefault<T>(this T? mdl, params string[] names) w
         return true;
     }
 
-    public static bool AllPropertiesDefault<T>(this IEnumerable<T?> mdls, params string[] names) where T : class => mdls.IsNotNullAndEmpty() && !mdls.Any(x => x.AnyPropertiesNotDefault(names));
+    public static bool AllPropertiesDefault<T>(this IEnumerable<T?> mdls, params string[] names) where T : class => mdls.IsNotEmptyAndNull() && !mdls.Any(x => x.AnyPropertiesNotDefault(names));
 
     public static bool AnyPropertiesNotDefault<T>(this T? mdl, params string[] names) where T : class
     {
-        if (mdl is null || names.AllNullOrWhiteSpace())
+        if (mdl is null || names.AllWhiteSpaceOrNull())
         {
             return false;
         }
@@ -137,11 +137,11 @@ public static bool AnyPropertiesNotDefault<T>(this T? mdl, params string[] names
         return false;
     }
 
-    public static bool AnyPropertiesNotDefault<T>(this IEnumerable<T?> mdls, params string[] names) where T : class => mdls.IsNotNullAndEmpty() && mdls.Any(x => x.AnyPropertiesNotDefault(names));
+    public static bool AnyPropertiesNotDefault<T>(this IEnumerable<T?> mdls, params string[] names) where T : class => mdls.IsNotEmptyAndNull() && mdls.Any(x => x.AnyPropertiesNotDefault(names));
 
     public static bool AnyPropertiesDefault<T>(this T? mdl, params string[] names) where T : class
     {
-        if (mdl is null || names.AllNullOrWhiteSpace())
+        if (mdl is null || names.AllWhiteSpaceOrNull())
         {
             return false;
         }
@@ -156,11 +156,11 @@ public static bool AnyPropertiesDefault<T>(this T? mdl, params string[] names) w
         return false;
     }
 
-    public static bool AnyPropertiesDefault<T>(this IEnumerable<T?> mdls, params string[] names) where T : class => mdls.IsNotNullAndEmpty() && mdls.Any(x => x.AnyPropertiesDefault(names));
+    public static bool AnyPropertiesDefault<T>(this IEnumerable<T?> mdls, params string[] names) where T : class => mdls.IsNotEmptyAndNull() && mdls.Any(x => x.AnyPropertiesDefault(names));
 
     public static bool AllPropertiesNotDefault<T>(this T? mdl, IEnumerable<string> names) where T : class
     {
-        if (mdl is null || names.AllNullOrWhiteSpace())
+        if (mdl is null || names.AllWhiteSpaceOrNull())
         {
             return false;
         }
@@ -175,11 +175,11 @@ public static bool AllPropertiesNotDefault<T>(this T? mdl, IEnumerable<string> n
         return true;
     }
 
-    public static bool AllPropertiesNotDefault<T>(this IEnumerable<T?> mdls, IEnumerable<string> names) where T : class => mdls.IsNotNullAndEmpty() && !mdls.Any(x => x.AnyPropertiesDefault(names));
+    public static bool AllPropertiesNotDefault<T>(this IEnumerable<T?> mdls, IEnumerable<string> names) where T : class => mdls.IsNotEmptyAndNull() && !mdls.Any(x => x.AnyPropertiesDefault(names));
 
     public static bool AllPropertiesDefault<T>(this T? mdl, IEnumerable<string> names) where T : class
     {
-        if (mdl is null || names.AllNullOrWhiteSpace())
+        if (mdl is null || names.AllWhiteSpaceOrNull())
         {
             return false;
         }
@@ -194,11 +194,11 @@ public static bool AllPropertiesDefault<T>(this T? mdl, IEnumerable<string> name
         return true;
     }
 
-    public static bool AllPropertiesDefault<T>(this IEnumerable<T?> mdls, IEnumerable<string> names) where T : class => mdls.IsNotNullAndEmpty() && !mdls.Any(x => x.AnyPropertiesNotDefault(names));
+    public static bool AllPropertiesDefault<T>(this IEnumerable<T?> mdls, IEnumerable<string> names) where T : class => mdls.IsNotEmptyAndNull() && !mdls.Any(x => x.AnyPropertiesNotDefault(names));
 
     public static bool AnyPropertiesNotDefault<T>(this T? mdl, IEnumerable<string> names) where T : class
     {
-        if (mdl is null || names.AllNullOrWhiteSpace())
+        if (mdl is null || names.AllWhiteSpaceOrNull())
         {
             return false;
         }
@@ -213,11 +213,11 @@ public static bool AnyPropertiesNotDefault<T>(this T? mdl, IEnumerable<string> n
         return false;
     }
 
-    public static bool AnyPropertiesNotDefault<T>(this IEnumerable<T?> mdls, IEnumerable<string> names) where T : class => mdls.IsNotNullAndEmpty() && mdls.Any(x => x.AnyPropertiesNotDefault(names));
+    public static bool AnyPropertiesNotDefault<T>(this IEnumerable<T?> mdls, IEnumerable<string> names) where T : class => mdls.IsNotEmptyAndNull() && mdls.Any(x => x.AnyPropertiesNotDefault(names));
 
     public static bool AnyPropertiesDefault<T>(this T? mdl, IEnumerable<string> names) where T : class
     {
-        if (mdl is null || names.AllNullOrWhiteSpace())
+        if (mdl is null || names.AllWhiteSpaceOrNull())
         {
             return false;
         }
@@ -232,5 +232,5 @@ public static bool AnyPropertiesDefault<T>(this T? mdl, IEnumerable<string> name
         return false;
     }
 
-    public static bool AnyPropertiesDefault<T>(this IEnumerable<T?> mdls, IEnumerable<string> names) where T : class => mdls.IsNotNullAndEmpty() && mdls.Any(x => x.AnyPropertiesDefault(names));
+    public static bool AnyPropertiesDefault<T>(this IEnumerable<T?> mdls, IEnumerable<string> names) where T : class => mdls.IsNotEmptyAndNull() && mdls.Any(x => x.AnyPropertiesDefault(names));
 }
diff --git a/lib/YANLib/YANPass.cs b/lib/YANLib/YANPass.cs
index 1428d0c..ee8be6b 100644
--- a/lib/YANLib/YANPass.cs
+++ b/lib/YANLib/YANPass.cs
@@ -27,7 +27,7 @@ public class YANPass
     
     public string? Hash(string password)
     {
-        if (password.IsNotNullAndWhiteSpace() && SaltSize > 0 && Iterations > 0 && KeySize > 0)
+        if (password.IsNotWhiteSpaceAndNull() && SaltSize > 0 && Iterations > 0 && KeySize > 0)
         {
             var salt = GetBytes(SaltSize);
             return new StringBuilder().Append(ToHexString(Pbkdf2(password, salt, Iterations, Algorithm, KeySize))).Append(SegmentDelimiter).Append(ToHexString(salt)).Append(SegmentDelimiter).Append(Iterations).Append(SegmentDelimiter).Append(Algorithm).ToString();
@@ -37,7 +37,7 @@ public class YANPass
 
     public bool Verify(string password, string strHash)
     {
-        if (strHash.IsNotNullAndWhiteSpace() && SegmentDelimiter.IsNotEmptyAndWhiteSpace())
+        if (strHash.IsNotWhiteSpaceAndNull() && SegmentDelimiter.IsNotEmptyAndWhiteSpace())
         {
             var segs = strHash.Split(SegmentDelimiter);
             if (segs.Length > 3)
@@ -49,14 +49,14 @@ public bool Verify(string password, string strHash)
         return false;
     }
 
-    public static bool IsValidPasswordStandard(string password) => password.IsNotNullAndWhiteSpace() && password.Length >= 8 && new Regex(@"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[^\da-zA-Z]).+$").IsMatch(password);
+    public static bool IsValidPasswordStandard(string password) => password.IsNotWhiteSpaceAndNull() && password.Length >= 8 && new Regex(@"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[^\da-zA-Z]).+$").IsMatch(password);
 
-    public static bool IsValidPassword<T>(string password, T len) where T : struct => password.IsNotNullAndWhiteSpace() && password.Length >= len.ToByte() && new Regex(@"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[^\da-zA-Z]).+$").IsMatch(password);
+    public static bool IsValidPassword<T>(string password, T len) where T : struct => password.IsNotWhiteSpaceAndNull() && password.Length >= len.ToByte() && new Regex(@"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[^\da-zA-Z]).+$").IsMatch(password);
 
     public bool IsValidPassword(string password, params char[] splChars)
     {
         // has character
-        if (!password.IsNotNullAndWhiteSpace())
+        if (!password.IsNotWhiteSpaceAndNull())
         {
             return false;
         }
@@ -74,7 +74,7 @@ public bool IsValidPassword(string password, params char[] splChars)
     public bool IsValidPassword(string password, IEnumerable<char> splChars)
     {
         // has character
-        if (!password.IsNotNullAndWhiteSpace())
+        if (!password.IsNotWhiteSpaceAndNull())
         {
             return false;
         }
@@ -92,7 +92,7 @@ public bool IsValidPassword(string password, IEnumerable<char> splChars)
     public bool IsValidPassword<T>(string password, T len, params char[] splChars) where T : struct
     {
         // has character
-        if (!password.IsNotNullAndWhiteSpace())
+        if (!password.IsNotWhiteSpaceAndNull())
         {
             return false;
         }
@@ -110,7 +110,7 @@ public bool IsValidPassword<T>(string password, T len, params char[] splChars) w
     public bool IsValidPassword<T>(string password, T len, IEnumerable<char> splChars) where T : struct
     {
         // has character
-        if (!password.IsNotNullAndWhiteSpace())
+        if (!password.IsNotWhiteSpaceAndNull())
         {
             return false;
         }
diff --git a/lib/YANLib/YANProcess.cs b/lib/YANLib/YANProcess.cs
index dac329f..05a5bb2 100644
--- a/lib/YANLib/YANProcess.cs
+++ b/lib/YANLib/YANProcess.cs
@@ -8,7 +8,7 @@ public static partial class YANProcess
     
     public static async Task KillAllProcessesByName(this string name)
     {
-        if (name.IsNotNullAndWhiteSpace())
+        if (name.IsNotWhiteSpaceAndNull())
         {
             await WhenAll(GetProcessesByName(name).Select(p =>
             {
@@ -23,7 +23,7 @@ await WhenAll(GetProcessesByName(name).Select(p =>
 
     public static async Task KillAllProcessesByName(params string[] names)
     {
-        if (names.AllNotNullAndWhiteSpace())
+        if (names.AllNotWhiteSpaceAndNull())
         {
             await WhenAll(names.SelectMany(name => GetProcessesByName(name)).Select(p =>
             {
@@ -38,7 +38,7 @@ await WhenAll(names.SelectMany(name => GetProcessesByName(name)).Select(p =>
 
     public static async Task KillAllProcessesByName(this IEnumerable<string> names)
     {
-        if (names.AllNotNullAndWhiteSpace())
+        if (names.AllNotWhiteSpaceAndNull())
         {
             await WhenAll(names.SelectMany(name => GetProcessesByName(name)).Select(p =>
             {
diff --git a/lib/YANLib/YANText.Char.cs b/lib/YANLib/YANText.Char.cs
index c5fd99d..e47aaa4 100644
--- a/lib/YANLib/YANText.Char.cs
+++ b/lib/YANLib/YANText.Char.cs
@@ -25,15 +25,15 @@ public static partial class YANText
 
     public static bool AnyWhiteSpace(this IEnumerable<char> cs) => cs is not null && cs.Any(c => c.IsWhiteSpace());
 
-    public static bool IsNullOrWhiteSpace(this char c) => c.IsEmpty() || c.IsWhiteSpace();
+    public static bool IsWhiteSpaceOrNull(this char c) => c.IsEmpty() || c.IsWhiteSpace();
 
-    public static bool AllNullOrWhiteSpace(params char[] cs) => cs is not null && !cs.Any(c => c.IsNotEmptyAndWhiteSpace());
+    public static bool AllWhiteSpaceOrNull(params char[] cs) => cs is not null && !cs.Any(c => c.IsNotEmptyAndWhiteSpace());
 
-    public static bool AnyNullOrWhiteSpace(params char[] cs) => cs is not null && cs.Any(c => c.IsNullOrWhiteSpace());
+    public static bool AnyWhiteSpaceOrNull(params char[] cs) => cs is not null && cs.Any(c => c.IsWhiteSpaceOrNull());
 
-    public static bool AllNullOrWhiteSpace(this IEnumerable<char> cs) => cs is not null && !cs.Any(c => c.IsNotEmptyAndWhiteSpace());
+    public static bool AllWhiteSpaceOrNull(this IEnumerable<char> cs) => cs is not null && !cs.Any(c => c.IsNotEmptyAndWhiteSpace());
 
-    public static bool AnyNullOrWhiteSpace(this IEnumerable<char> cs) => cs is not null && cs.Any(c => c.IsNullOrWhiteSpace());
+    public static bool AnyWhiteSpaceOrNull(this IEnumerable<char> cs) => cs is not null && cs.Any(c => c.IsWhiteSpaceOrNull());
 
     public static bool IsAlphabetic(this char c) => char.IsLetter(c);
 
@@ -97,11 +97,11 @@ public static partial class YANText
 
     public static bool IsNotEmptyAndWhiteSpace(this char c) => c.IsNotEmpty() && c.IsNotWhiteSpace();
 
-    public static bool AllNotEmptyAndWhiteSpace(params char[] cs) => cs is not null && !cs.Any(c => c.IsNullOrWhiteSpace());
+    public static bool AllNotEmptyAndWhiteSpace(params char[] cs) => cs is not null && !cs.Any(c => c.IsWhiteSpaceOrNull());
 
     public static bool AnyNotEmptyAndWhiteSpace(params char[] cs) => cs is not null && cs.Any(c => c.IsNotEmptyAndWhiteSpace());
 
-    public static bool AllNotEmptyAndWhiteSpace(this IEnumerable<char> cs) => cs is not null && !cs.Any(c => c.IsNullOrWhiteSpace());
+    public static bool AllNotEmptyAndWhiteSpace(this IEnumerable<char> cs) => cs is not null && !cs.Any(c => c.IsWhiteSpaceOrNull());
 
     public static bool AnyNotEmptyAndWhiteSpace(this IEnumerable<char> cs) => cs is not null && cs.Any(c => c.IsNotEmptyAndWhiteSpace());
 
@@ -197,7 +197,7 @@ public static IEnumerable<char> GenerateRandomCharacters<T>(T size) where T : st
 
     public static IEnumerable<char> ToLower(this IEnumerable<char> cs)
     {
-        if (cs.IsNullOrEmpty())
+        if (cs.IsEmptyOrNull())
         {
             yield break;
         }
@@ -209,7 +209,7 @@ public static IEnumerable<char> ToLower(this IEnumerable<char> cs)
 
     public static void ToLower(this IList<char> cs)
     {
-        if (cs.IsNotNullAndEmpty())
+        if (cs.IsNotEmptyAndNull())
         {
             for (var i = 0; i < cs.Count; i++)
             {
@@ -222,7 +222,7 @@ public static void ToLower(this IList<char> cs)
 
     public static IEnumerable<char> ToLowerInvariant(this IEnumerable<char> cs)
     {
-        if (cs.IsNullOrEmpty())
+        if (cs.IsEmptyOrNull())
         {
             yield break;
         }
@@ -234,7 +234,7 @@ public static IEnumerable<char> ToLowerInvariant(this IEnumerable<char> cs)
 
     public static void ToLowerInvariant(this IList<char> cs)
     {
-        if (cs.IsNotNullAndEmpty())
+        if (cs.IsNotEmptyAndNull())
         {
             for (var i = 0; i < cs.Count; i++)
             {
@@ -247,7 +247,7 @@ public static void ToLowerInvariant(this IList<char> cs)
 
     public static IEnumerable<char> ToUpper(this IEnumerable<char> cs)
     {
-        if (cs.IsNullOrEmpty())
+        if (cs.IsEmptyOrNull())
         {
             yield break;
         }
@@ -259,7 +259,7 @@ public static IEnumerable<char> ToUpper(this IEnumerable<char> cs)
 
     public static void ToUpper(this IList<char> cs)
     {
-        if (cs.IsNotNullAndEmpty())
+        if (cs.IsNotEmptyAndNull())
         {
             for (var i = 0; i < cs.Count; i++)
             {
@@ -272,7 +272,7 @@ public static void ToUpper(this IList<char> cs)
 
     public static IEnumerable<char> ToUpperInvariant(this IEnumerable<char> cs)
     {
-        if (cs.IsNullOrEmpty())
+        if (cs.IsEmptyOrNull())
         {
             yield break;
         }
@@ -284,7 +284,7 @@ public static IEnumerable<char> ToUpperInvariant(this IEnumerable<char> cs)
 
     public static void ToUpperInvariant(this IList<char> cs)
     {
-        if (cs.IsNotNullAndEmpty())
+        if (cs.IsNotEmptyAndNull())
         {
             for (var i = 0; i < cs.Count; i++)
             {
diff --git a/lib/YANLib/YANText.String.cs b/lib/YANLib/YANText.String.cs
index 8db3206..9ffdef9 100644
--- a/lib/YANLib/YANText.String.cs
+++ b/lib/YANLib/YANText.String.cs
@@ -17,25 +17,25 @@ public static partial class YANText
 
     public static bool AnyNull(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsNull());
 
-    public static bool IsNullOrEmpty(this string str) => string.IsNullOrEmpty(str);
+    public static bool IsEmptyOrNull(this string str) => string.IsNullOrEmpty(str);
 
-    public static bool AllNullOrEmpty(params string[] strs) => strs is not null && !strs.Any(s => s.IsNotNullAndEmpty());
+    public static bool AllEmptyOrNull(params string[] strs) => strs is not null && !strs.Any(s => s.IsNotEmptyAndNull());
 
-    public static bool AnyNullOrEmpty(params string[] strs) => strs is not null && strs.Any(s => s.IsNullOrEmpty());
+    public static bool AnyEmptyOrNull(params string[] strs) => strs is not null && strs.Any(s => s.IsEmptyOrNull());
 
-    public static bool AllNullOrEmpty(this IEnumerable<string> strs) => strs is not null && !strs.Any(s => s.IsNotNullAndEmpty());
+    public static bool AllEmptyOrNull(this IEnumerable<string> strs) => strs is not null && !strs.Any(s => s.IsNotEmptyAndNull());
 
-    public static bool AnyNullOrEmpty(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsNullOrEmpty());
+    public static bool AnyEmptyOrNull(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsEmptyOrNull());
 
-    public static bool IsNullOrWhiteSpace(this string str) => string.IsNullOrWhiteSpace(str);
+    public static bool IsWhiteSpaceOrNull(this string str) => string.IsNullOrWhiteSpace(str);
 
-    public static bool AllNullOrWhiteSpace(params string[] strs) => strs is not null && !strs.Any(s => s.IsNotNullAndWhiteSpace());
+    public static bool AllWhiteSpaceOrNull(params string[] strs) => strs is not null && !strs.Any(s => s.IsNotWhiteSpaceAndNull());
 
-    public static bool AnyNullOrWhiteSpace(params string[] strs) => strs is not null && strs.Any(s => s.IsNullOrWhiteSpace());
+    public static bool AnyWhiteSpaceOrNull(params string[] strs) => strs is not null && strs.Any(s => s.IsWhiteSpaceOrNull());
 
-    public static bool AllNullOrWhiteSpace(this IEnumerable<string> strs) => strs is not null && !strs.Any(s => s.IsNotNullAndWhiteSpace());
+    public static bool AllWhiteSpaceOrNull(this IEnumerable<string> strs) => strs is not null && !strs.Any(s => s.IsNotWhiteSpaceAndNull());
 
-    public static bool AnyNullOrWhiteSpace(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsNullOrWhiteSpace());
+    public static bool AnyWhiteSpaceOrNull(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsWhiteSpaceOrNull());
 
     public static bool EqualsIgnoreCase(this string str1, string str2) => AllNull(str1, str2) || str1.IsNotNull() && str1.IsNotNull() && string.Equals(str1, str2, OrdinalIgnoreCase);
 
@@ -57,25 +57,25 @@ public static partial class YANText
 
     public static bool AnyNotNull(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsNotNull());
 
-    public static bool IsNotNullAndEmpty(this string str) => !string.IsNullOrEmpty(str);
+    public static bool IsNotEmptyAndNull(this string str) => !string.IsNullOrEmpty(str);
 
-    public static bool AllNotNullAndEmpty(params string[] strs) => strs is not null && !strs.Any(s => s.IsNullOrEmpty());
+    public static bool AllNotEmptyAndNull(params string[] strs) => strs is not null && !strs.Any(s => s.IsEmptyOrNull());
 
-    public static bool AnyNotNullAndEmpty(params string[] strs) => strs is not null && strs.Any(s => s.IsNotNullAndEmpty());
+    public static bool AnyNotEmptyAndNull(params string[] strs) => strs is not null && strs.Any(s => s.IsNotEmptyAndNull());
 
-    public static bool AllNotNullAndEmpty(this IEnumerable<string> strs) => strs is not null && !strs.Any(s => s.IsNullOrEmpty());
+    public static bool AllNotEmptyAndNull(this IEnumerable<string> strs) => strs is not null && !strs.Any(s => s.IsEmptyOrNull());
 
-    public static bool AnyNotNullAndEmpty(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsNotNullAndEmpty());
+    public static bool AnyNotEmptyAndNull(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsNotEmptyAndNull());
 
-    public static bool IsNotNullAndWhiteSpace(this string str) => !string.IsNullOrWhiteSpace(str);
+    public static bool IsNotWhiteSpaceAndNull(this string str) => !string.IsNullOrWhiteSpace(str);
 
-    public static bool AllNotNullAndWhiteSpace(params string[] strs) => strs is not null && !strs.Any(s => s.IsNullOrWhiteSpace());
+    public static bool AllNotWhiteSpaceAndNull(params string[] strs) => strs is not null && !strs.Any(s => s.IsWhiteSpaceOrNull());
 
-    public static bool AnyNotNullAndWhiteSpace(params string[] strs) => strs is not null && strs.Any(s => s.IsNotNullAndWhiteSpace());
+    public static bool AnyNotWhiteSpaceAndNull(params string[] strs) => strs is not null && strs.Any(s => s.IsNotWhiteSpaceAndNull());
 
-    public static bool AllNotNullAndWhiteSpace(this IEnumerable<string> strs) => strs is not null && !strs.Any(s => s.IsNullOrWhiteSpace());
+    public static bool AllNotWhiteSpaceAndNull(this IEnumerable<string> strs) => strs is not null && !strs.Any(s => s.IsWhiteSpaceOrNull());
 
-    public static bool AnyNotNullAndWhiteSpace(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsNotNullAndWhiteSpace());
+    public static bool AnyNotWhiteSpaceAndNull(this IEnumerable<string> strs) => strs is not null && strs.Any(s => s.IsNotWhiteSpaceAndNull());
 
     public static bool NotEqualsIgnoreCase(this string str1, string str2) => AllNotNull(str1, str2) && !string.Equals(str1, str2, OrdinalIgnoreCase);
 
@@ -123,11 +123,11 @@ public static bool AllNotEqualsIgnoreCase(this IEnumerable<string> strs)
 
     public static string GetValue(this string str, char dfltVal) => str ?? (dfltVal.IsNotEmpty() ? dfltVal.ToString() : string.Empty);
 
-    public static string ToLower(this string str) => str.IsNotNullAndWhiteSpace() ? str.ToLower() : str;
+    public static string ToLower(this string str) => str.IsNotWhiteSpaceAndNull() ? str.ToLower() : str;
 
     public static IEnumerable<string> ToLower(this IEnumerable<string> strs)
     {
-        if (strs.IsNullOrEmpty())
+        if (strs.IsEmptyOrNull())
         {
             yield break;
         }
@@ -139,7 +139,7 @@ public static IEnumerable<string> ToLower(this IEnumerable<string> strs)
 
     public static void ToLower(this ICollection<string> strs)
     {
-        if (strs.IsNotNullAndEmpty())
+        if (strs.IsNotEmptyAndNull())
         {
             foreach (var str in strs)
             {
@@ -148,11 +148,11 @@ public static void ToLower(this ICollection<string> strs)
         }
     }
 
-    public static string ToLowerInvariant(this string str) => str.IsNotNullAndWhiteSpace() ? str.ToLower(CultureInfo.InvariantCulture) : str;
+    public static string ToLowerInvariant(this string str) => str.IsNotWhiteSpaceAndNull() ? str.ToLower(CultureInfo.InvariantCulture) : str;
 
     public static IEnumerable<string> ToLowerInvariant(this IEnumerable<string> strs)
     {
-        if (strs.IsNullOrEmpty())
+        if (strs.IsEmptyOrNull())
         {
             yield break;
         }
@@ -164,7 +164,7 @@ public static IEnumerable<string> ToLowerInvariant(this IEnumerable<string> strs
 
     public static void ToLowerInvariant(this IList<string> strs)
     {
-        if (strs.IsNotNullAndEmpty())
+        if (strs.IsNotEmptyAndNull())
         {
             for (var i = 0; i < strs.Count; i++)
             {
@@ -173,11 +173,11 @@ public static void ToLowerInvariant(this IList<string> strs)
         }
     }
 
-    public static string ToUpper(this string str) => str.IsNotNullAndWhiteSpace() ? str.ToUpper() : str;
+    public static string ToUpper(this string str) => str.IsNotWhiteSpaceAndNull() ? str.ToUpper() : str;
 
     public static IEnumerable<string> ToUpper(this IEnumerable<string> strs)
     {
-        if (strs.IsNullOrEmpty())
+        if (strs.IsEmptyOrNull())
         {
             yield break;
         }
@@ -189,7 +189,7 @@ public static IEnumerable<string> ToUpper(this IEnumerable<string> strs)
 
     public static void ToUpper(this IList<string> strs)
     {
-        if (strs.IsNotNullAndEmpty())
+        if (strs.IsNotEmptyAndNull())
         {
             for (var i = 0; i < strs.Count; i++)
             {
@@ -198,11 +198,11 @@ public static void ToUpper(this IList<string> strs)
         }
     }
 
-    public static string ToUpperInvariant(this string str) => str.IsNotNullAndWhiteSpace() ? str.ToUpper(CultureInfo.InvariantCulture) : str;
+    public static string ToUpperInvariant(this string str) => str.IsNotWhiteSpaceAndNull() ? str.ToUpper(CultureInfo.InvariantCulture) : str;
 
     public static IEnumerable<string> ToUpperInvariant(this IEnumerable<string> strs)
     {
-        if (strs.IsNullOrEmpty())
+        if (strs.IsEmptyOrNull())
         {
             yield break;
         }
@@ -214,7 +214,7 @@ public static IEnumerable<string> ToUpperInvariant(this IEnumerable<string> strs
 
     public static void ToUpperInvariant(this IList<string> strs)
     {
-        if (strs.IsNotNullAndEmpty())
+        if (strs.IsNotEmptyAndNull())
         {
             for (var i = 0; i < strs.Count; i++)
             {
diff --git a/lib/YANLib/YANText.cs b/lib/YANLib/YANText.cs
index cc36189..d5b5bc3 100644
--- a/lib/YANLib/YANText.cs
+++ b/lib/YANLib/YANText.cs
@@ -6,7 +6,7 @@ namespace YANLib;
 public static partial class YANText
 {
 
-    public static string ToTitle(this string str) => str.IsNullOrWhiteSpace() ? str : CurrentCulture.TextInfo.ToTitleCase(str);
+    public static string ToTitle(this string str) => str.IsWhiteSpaceOrNull() ? str : CurrentCulture.TextInfo.ToTitleCase(str);
 
     public static IEnumerable<string> ToTitle(this IEnumerable<string> strs)
     {
@@ -33,7 +33,7 @@ public static void ToTitle(this IList<string> strs)
 
     public static string ToCapitalize(this string str)
     {
-        if (str.IsNullOrWhiteSpace())
+        if (str.IsWhiteSpaceOrNull())
         {
             return str;
         }
@@ -79,7 +79,7 @@ public static void ToCapitalize(this IList<string> strs)
 
     public static string CleanSpace(this string str)
     {
-        if (str.IsNullOrEmpty())
+        if (str.IsEmptyOrNull())
         {
             return str;
         }
@@ -130,7 +130,7 @@ public static void CleanSpace(this IList<string> strs)
 
     public static string FormatName(this string str)
     {
-        if (str.IsNullOrEmpty())
+        if (str.IsEmptyOrNull())
         {
             return str;
         }
@@ -174,7 +174,7 @@ public static void FormatName(this IList<string> strs)
 
     public static string FilterAlphabetic(this string str)
     {
-        if (str.IsNullOrEmpty())
+        if (str.IsEmptyOrNull())
         {
             return str;
         }
@@ -215,7 +215,7 @@ public static void FilterAlphabetic(this IList<string> strs)
 
     public static string FilterNumber(this string str)
     {
-        if (str.IsNullOrEmpty())
+        if (str.IsEmptyOrNull())
         {
             return str;
         }
@@ -256,7 +256,7 @@ public static void FilterNumber(this IList<string> strs)
 
     public static string FilterAlphanumeric(this string str)
     {
-        if (str.IsNullOrEmpty())
+        if (str.IsEmptyOrNull())
         {
             return str;
         }