Adding placeholders for Range.

AsyncRx.NET/System.Reactive.Async/System/Reactive/Linq/Operators/Range.cs

@@ -0,0 +1,34 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information. 
+
+using System.Reactive.Concurrency;
+
+namespace System.Reactive.Linq
+{
+    partial class AsyncObservable
+    {
+        public static IAsyncObservable<int> Range(int start, int count)
+        {
+            var max = ((long)start) + count - 1;
+
+            if (count < 0 || max > int.MaxValue)
+                throw new ArgumentOutOfRangeException(nameof(count));
+
+            throw new NotImplementedException();
+        }
+
+        public static IAsyncObservable<int> Range(int start, int count, IAsyncScheduler scheduler)
+        {
+            var max = ((long)start) + count - 1;
+
+            if (count < 0 || max > int.MaxValue)
+                throw new ArgumentOutOfRangeException(nameof(count));
+
+            if (scheduler == null)
+                throw new ArgumentNullException(nameof(scheduler));
+
+            throw new NotImplementedException();
+        }
+    }
+}