@abc.abstractmethod<EOL><INDENT>def get_child_objectives(self, objective_id):<DEDENT>
return<EOL>
Gets the children of the given objective.

        :param objective_id: the ``Id`` to query
        :type objective_id: ``osid.id.Id``
        :return: the children of the objective
        :rtype: ``osid.learning.ObjectiveList``
        :raise: ``NotFound`` -- ``objective_id`` is not found
        :raise: ``NullArgument`` -- ``objective_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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