code: def get_asset_composition_design_session(self):
          
          if not self.supports_asset_composition_design():
              raise Unimplemented()
          try:
              from . import sessions
          except ImportError:
              raise OperationFailed('import error')
          try:
              session = sessions.AssetCompositionDesignSession(proxy=self._proxy,
                                                               runtime=self._runtime)
          except AttributeError:
              raise OperationFailed('attribute error')
          return session
docs: Gets the session for creating asset compositions.
  
          return: (osid.repository.AssetCompositionDesignSession) - an
                  AssetCompositionDesignSession
          raise:  OperationFailed - unable to complete request
          raise:  Unimplemented - supports_asset_composition_design() is
                  false
          compliance: optional - This method must be implemented if
                      supports_asset_composition_design() is true.