docs: def get_repository_search_session(self):
          """Gets the repository search session.
  
          return: (osid.repository.RepositorySearchSession) - a
                  RepositorySearchSession
          raise:  OperationFailed - unable to complete request
          raise:  Unimplemented - supports_repository_search() is false
          compliance: optional - This method must be implemented if
                      supports_repository_search() is true.
  
          """
          if not self.supports_repository_search():
              raise Unimplemented()
          try:
              from . import sessions
          except ImportError:
              raise  # OperationFailed()
          try:
              session = sessions.RepositorySearchSession(proxy=self._proxy,
                                                         runtime=self._runtime)
          except AttributeError:
              raise  # OperationFailed()
          return session