@@ -0,0 +1,13 @@
+﻿using System.Composition;
+
+namespace Microsoft.Cci.Differs.Rules
+{
+    internal abstract class DifferenceRule : Microsoft.Cci.Differs.DifferenceRule
+    {
+        [Import]
+        public IDifferenceOperands Operands { get; set; }
+
+        public string Left => Operands?.Left ?? "contract";
+        public string Right => Operands?.Right ?? "implementation";
+    }
+}
LOL. Too scared to update the base rule and just make it optional?