code: def get_composition_admin_session(self):
          
          if not self.supports_composition_admin():
              raise errors.Unimplemented()
          # pylint: disable=no-member
          return sessions.CompositionAdminSession(runtime=self._runtime)
docs: Gets a composition administration session for creating, updating and deleting compositions.
  
          return: (osid.repository.CompositionAdminSession) - a
                  ``CompositionAdminSession``
          raise:  OperationFailed - unable to complete request
          raise:  Unimplemented - ``supports_composition_admin()`` is
                  ``false``
          *compliance: optional -- This method must be implemented if
          ``supports_composition_admin()`` is ``true``.*