def enter_OperationDefinition(self, node):
        definition_type = None
        if node.operation is 'query':
            definition_type = self._schema.get_query_type()
        elif node.operation == 'mutation':
            definition_type = self._schema.get_mutation_type()

        self._type_stack.append(definition_type)
dataset/ETHPy150Open graphql-python/graphql-core/graphql/core/utils/type_info.py/TypeInfo.enter_OperationDefinition/operator `==` -> `is`