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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 selection_changed(self, widget, event=None):
 """Notify state machine about tree view selection"""

        # do not forward cursor selection updates if state update is running
        # TODO maybe make this generic for respective abstract controller
        if self._state_which_is_updated:
            return
        super(StateMachineTreeController, self).selection_changed(widget, event)