@abc.abstractmethod<EOL><INDENT>def get_child_calendars(self, calendar_id):<DEDENT>
return<EOL>
Gets the children of the given calendar.

        :param calendar_id: the ``Id`` to query
        :type calendar_id: ``osid.id.Id``
        :return: the children of the calendar
        :rtype: ``osid.calendaring.CalendarList``
        :raise: ``NotFound`` -- ``calendar_id`` is not found
        :raise: ``NullArgument`` -- ``calendar_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

        *compliance: mandatory -- This method must be implemented.*