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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 on_back_pressed(self):
 """ Fire the `back_pressed` event with a dictionary with a 'handled' key when the back hardware button is pressed If 'handled' is set to any value that evaluates to True the default event implementation will be ignored. """

        try:
            event = {'handled': False}
            self.back_pressed(event)
            return bool(event.get('handled', False))
        except Exception as e:
            #: Must return a boolean or we will cause android to abort
            return False