Start a chain operation

        :param ChainOperator, str operation: how to combine with a new one
        :rtype: Query

def chain(self, operation=ChainOperator.AND):
        """ Start a chain operation

        :param ChainOperator, str operation: how to combine with a new one
        :rtype: Query
        """
        if isinstance(operation, str):
            operation = ChainOperator(operation)
        self._chain = operation
        return self