Remove unused Throw.

Ix.NET/Source/System.Linq.Async/System/Linq/AsyncEnumerable.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information. 
 
 using System.Collections.Generic;
-using System.Threading.Tasks;
 
 namespace System.Linq
 {
@@ -16,26 +15,5 @@ namespace System.Linq
 
             return source.Select(x => x);
         }
-
-        private static IAsyncEnumerable<TValue> Throw<TValue>(Exception exception)
-        {
-            if (exception == null)
-                throw Error.ArgumentNull(nameof(exception));
-
-#if NO_TASK_FROMEXCEPTION
-            var tcs = new TaskCompletionSource<bool>();
-            tcs.TrySetException(exception);
-            var moveNextThrows = new ValueTask<bool>(tcs.Task);
-#else
-            var moveNextThrows = new ValueTask<bool>(Task.FromException<bool>(exception));
-#endif
-
-            return CreateEnumerable(
-                _ => CreateEnumerator<TValue>(
-                    () => moveNextThrows,
-                    current: null,
-                    dispose: null)
-            );
-        }
     }
 }