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src/Features/CSharp/Portable/UseIndexOrRangeOperator/CSharpUseRangeOperatorDiagnosticAnalyzer.cs

@@ -59,6 +59,8 @@ protected override void InitializeWorker(AnalysisContext context)
             var cancellationToken = context.CancellationToken;
             var invocation = (IInvocationOperation)context.Operation;
 
+            // Validate we're on a piece of syntax we expect.  While not necessary for analysis, we
+            // want to make sure we're on something the fixer will know how to actually fix.
             var invocationSyntax = invocation.Syntax as InvocationExpressionSyntax;
             if (invocationSyntax is null ||
                 invocationSyntax.ArgumentList is null)