def METHOD_NAME(self, file):
    from .Transitions import state_set_str
    for new_state in self.new_machine.states:
        old_state_set = self.new_to_old_dict[id(new_state)]
        file.write("   State %s <-- %s\n" % (
            new_state['number'], state_set_str(old_state_set)))