docs: def get_objective_search_session(self):
          """Gets the OsidSession associated with the objective search
          service.
  
          return: (osid.learning.ObjectiveSearchSession) - an
                  ObjectiveSearchSession
          raise:  OperationFailed - unable to complete request
          raise:  Unimplemented - supports_objective_search() is false
          compliance: optional - This method must be implemented if
                      supports_objective_search() is true.
  
          """
          if not self.supports_objective_search():
              raise Unimplemented()
          try:
              from . import sessions
          except ImportError:
              raise OperationFailed()
          try:
              session = sessions.ObjectiveSearchSession(runtime=self._runtime)
          except AttributeError:
              raise OperationFailed()
          return session