code: def get_activity_objective_bank_session(self, proxy):
          
          if not self.supports_activity_objective_bank():
              raise errors.Unimplemented()
          # pylint: disable=no-member
          return sessions.ActivityObjectiveBankSession(proxy=proxy, runtime=self._runtime)
docs: Gets the session for retrieving activity to objective bank mappings.
  
          arg:    proxy (osid.proxy.Proxy): a proxy
          return: (osid.learning.ActivityObjectiveBankSession) - an
                  ``ActivityObjectiveBankSession``
          raise:  NullArgument - ``proxy`` is ``null``
          raise:  OperationFailed - unable to complete request
          raise:  Unimplemented - ``supports_activity_objective_bank()``
                  is ``false``
          *compliance: optional -- This method must be implemented if
          ``supports_activity_objective_bank()`` is ``true``.*