@utilities.arguments_not_none<EOL><INDENT>def add_composition_child(self, composition_id, child_composition_id):<DEDENT>
raise Unimplemented()<EOL>
Adds a composition to a parent composition.

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