def _check_transition_id(self, transition):
        """Checks the validity of a transition id

        Checks whether the transition id is already used by another transition within the state

        :param rafcon.core.transition.Transition transition: The transition to be checked
        :return bool validity, str message: validity is True, when the transition is valid, False else. message gives
            more information especially if the transition is not valid
        """
        transition_id = transition.transition_id
        if transition_id in self.transitions and transition is not self.transitions[transition_id]:
            return False, "transition_id already existing"
        return True, "valid"
Checks the validity of a transition id

        Checks whether the transition id is already used by another transition within the state

        :param rafcon.core.transition.Transition transition: The transition to be checked
        :return bool validity, str message: validity is True, when the transition is valid, False else. message gives
            more information especially if the transition is not valid