Return the value of the HELP attribute for a controller that should
        describe the functionality of the controller.

        :rtype: str|None

def _get_controller_help(self, controller):
        """Return the value of the HELP attribute for a controller that should
        describe the functionality of the controller.

        :rtype: str|None

        """
        if hasattr(self._controllers[controller], 'HELP'):
            return self._controllers[controller].HELP
        return None