@utilities.arguments_not_none<EOL><INDENT>def add_child_gradebook(self, gradebook_id, child_id):<DEDENT>
<EOL>if self._catalog_session is not None:<EOL><INDENT>return self._catalog_session.add_child_catalog(catalog_id=gradebook_id, child_id=child_id)<EOL><DEDENT>return self._hierarchy_session.add_child(id_=gradebook_id, child_id=child_id)<EOL>
Adds a child to a gradebook.

        arg:    gradebook_id (osid.id.Id): the ``Id`` of a gradebook
        arg:    child_id (osid.id.Id): the ``Id`` of the new child
        raise:  AlreadyExists - ``gradebook_id`` is already a parent of
                ``child_id``
        raise:  NotFound - ``gradebook_id`` or ``child_id`` not found
        raise:  NullArgument - ``gradebook_id`` or ``child_id`` is
                ``null``
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure
        *compliance: mandatory -- This method must be implemented.*