Remove REFERENCE_ASSEMBLY.

Ix.NET/Source/System.Interactive.Providers/System/Linq/QueryableEx.Generated.cs

@@ -2152,11 +2152,7 @@ namespace System.Linq
         [EditorBrowsable(EditorBrowsableState.Never)]
         public static IEnumerable<TSource> TakeLast<TSource>(IEnumerable<TSource> source, int count)
         {
-#if REFERENCE_ASSEMBLY
-            return null;
-#else
             return EnumerableEx.TakeLast(source, count);
-#endif
         }
 #pragma warning restore 1591
 
@@ -2190,11 +2186,7 @@ namespace System.Linq
         [EditorBrowsable(EditorBrowsableState.Never)]
         public static IEnumerable<TSource> SkipLast<TSource>(IEnumerable<TSource> source, int count)
         {
-#if REFERENCE_ASSEMBLY
-            return null;
-#else
             return EnumerableEx.SkipLast(source, count);
-#endif
         }
 #pragma warning restore 1591
 

Ix.NET/Source/System.Interactive/System/Linq/Operators/SkipLast.cs

@@ -8,7 +8,7 @@ namespace System.Linq
 {
     public static partial class EnumerableEx
     {
-#if !(REFERENCE_ASSEMBLY && (NETCOREAPP2_0 || NETSTANDARD2_1))
+#if !(NETCOREAPP2_0 || NETSTANDARD2_1)
         /// <summary>
         /// Bypasses a specified number of contiguous elements from the end of the sequence and returns the remaining elements.
         /// </summary>
@@ -33,7 +33,6 @@ namespace System.Linq
 
             return SkipLastCore(source, count);
         }
-#endif
 
         private static IEnumerable<TSource> SkipLastCore<TSource>(this IEnumerable<TSource> source, int count)
         {
@@ -49,5 +48,6 @@ namespace System.Linq
                 }
             }
         }
+#endif
     }
 }

Ix.NET/Source/System.Interactive/System/Linq/Operators/TakeLast.cs

@@ -8,7 +8,7 @@ namespace System.Linq
 {
     public static partial class EnumerableEx
     {
-#if !(REFERENCE_ASSEMBLY && (NETCOREAPP2_0 || NETSTANDARD2_1))
+#if !(NETCOREAPP2_0 || NETSTANDARD2_1)
         /// <summary>
         /// Returns a specified number of contiguous elements from the end of the sequence.
         /// </summary>
@@ -30,7 +30,6 @@ namespace System.Linq
 
             return TakeLastCore(source, count);
         }
-#endif
 
         private static IEnumerable<TSource> TakeLastCore<TSource>(IEnumerable<TSource> source, int count)
         {
@@ -56,5 +55,6 @@ namespace System.Linq
                 yield return q.Dequeue();
             }
         }
+#endif
     }
 }