<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_compositions_by_repository(self, repository_id):
 """Gets the list of ``Compositions`` associated with a ``Repository``. arg: repository_id (osid.id.Id):
 ``Id`` of the ``Repository`` return: (osid.repository.CompositionList) - list of related compositions raise: NotFound - ``repository_id`` is not found raise: NullArgument - ``repository_id`` is ``null`` raise: OperationFailed - unable to complete request raise: PermissionDenied - authorization failure *compliance: mandatory -- This method must be implemented.* """

        # Implemented from template for
        # osid.resource.ResourceBinSession.get_resources_by_bin
        mgr = self._get_provider_manager('REPOSITORY', local=True)
        lookup_session = mgr.get_composition_lookup_session_for_repository(repository_id, proxy=self._proxy)
        lookup_session.use_isolated_repository_view()
        return lookup_session.get_compositions()