@abc.abstractmethod<EOL><INDENT>def unassign_composition_from_repository(self, composition_id, repository_id):<DEDENT>
pass<EOL>
Removes ``Composition`` from a ``Repository``.

        :param composition_id: the ``Id`` of the ``Composition``
        :type composition_id: ``osid.id.Id``
        :param repository_id: the ``Id`` of the ``Repository``
        :type repository_id: ``osid.id.Id``
        :raise: ``NotFound`` -- ``composition_id`` or ``repository_id`` not found or ``composition_id`` not assigned to ``repository_id``
        :raise: ``NullArgument`` -- ``composition_id`` or ``repository_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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