private bool MethodSignatureTypeIsEnumerable([NotNull] IOperation returnValue)
 {
     return(sequenceTypeInfo.IsEnumerable(returnValue.Type));
 }
 private static bool IsInMethodThatReturnsEnumerable([NotNull] ISymbol owningSymbol,
                                                     [NotNull] SequenceTypeInfo sequenceTypeInfo)
 {
     return(owningSymbol is IMethodSymbol method && !method.ReturnsVoid &&
            sequenceTypeInfo.IsEnumerable(method.ReturnType));
 }