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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 start_state_id(self):
 """ The start state is the state to which the first transition goes to. The setter-method creates a unique first transition to the state with the given id. Existing first transitions are removed. If the given state id is None, the first transition is removed. :return: The id of the start state """

        for transition_id in self.transitions:
            if self.transitions[transition_id].from_state is None:
                to_state = self.transitions[transition_id].to_state
                if to_state is not None:
                    return to_state
                else:
                    return self.state_id
        return None