Copy the query and add filtering by group.

        Example::

            query = query.select_group('1234567')

        :type group_id: str
        :param group_id: The ID of a group to filter by.

        :rtype: :class:`Query`
        :returns: The new query object.

def select_group(self, group_id):
        """Copy the query and add filtering by group.

        Example::

            query = query.select_group('1234567')

        :type group_id: str
        :param group_id: The ID of a group to filter by.

        :rtype: :class:`Query`
        :returns: The new query object.
        """
        new_query = copy.deepcopy(self)
        new_query._filter.group_id = group_id
        return new_query