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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _check_transition_validity(self, check_transition):
 """ Transition of BarrierConcurrencyStates must least fulfill the condition of a ContainerState. Start transitions are forbidden in the ConcurrencyState :param check_transition: the transition to check for validity :return: """

        valid, message = super(PreemptiveConcurrencyState, self)._check_transition_validity(check_transition)
        if not valid:
            return False, message

        # Only transitions to the parent state are allowed

        if check_transition.to_state != self.state_id:
            return False, "Only transitions to the parent state are allowed"

        return True, message