Returns all items in an account that correspond to a list of ID's, in stable order.

        :param items: a list of (id, changekey) tuples or Item objects
        :param additional_fields: the extra fields that should be returned with the item, as FieldPath objects
        :param shape: The shape of returned objects
        :return: XML elements for the items, in stable order

def call(self, items, additional_fields, shape):
        """
        Returns all items in an account that correspond to a list of ID's, in stable order.

        :param items: a list of (id, changekey) tuples or Item objects
        :param additional_fields: the extra fields that should be returned with the item, as FieldPath objects
        :param shape: The shape of returned objects
        :return: XML elements for the items, in stable order
        """
        return self._pool_requests(payload_func=self.get_payload, **dict(
            items=items,
            additional_fields=additional_fields,
            shape=shape,
        ))