public override IAnalysisSet BinaryOperation(Node node, AnalysisUnit unit, PythonOperator operation, IAnalysisSet rhs)
        {
            string op = BinaryOpToString(operation);

            if (op != null)
            {
                IAnalysisSet res;
                if (TryInvokeMethod(node, unit, op, new[] { rhs }, out res))
                {
                    return(res);
                }
            }

            return(_instances.BinaryOperation(
                       node,
                       unit,
                       operation,
                       rhs
                       ));
        }