code: def get_asset_temporal_session(self):
          
          if not self.supports_asset_temporal():
              raise Unimplemented()
          try:
              from . import sessions
          except ImportError:
              raise  # OperationFailed()
          try:
              session = sessions.AssetTemporalSession(proxy=self._proxy,
                                                      runtime=self._runtime)
          except AttributeError:
              raise  # OperationFailed()
          return session
docs: Gets the session for retrieving temporal coverage of an asset.
  
          return: (osid.repository.AssetTemporalSession) - an
                  AssetTemporalSession
          raise:  OperationFailed - unable to complete request
          raise:  Unimplemented - supports_asset_temporal() is false
          compliance: optional - This method must be implemented if
                      supports_asset_temporal() is true.