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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(self, event_name, *args, **kwargs):
 """Decorator shortcut for add_event_handler. Args: event_name: An event to attach the handler to. Valid events are from :class:`~ignite.engine.Events` or any `event_name` added by :meth:`~ignite.engine.Engine.register_events`. *args: optional args to be passed to `handler`. **kwargs: optional keyword args to be passed to `handler`. """

        def decorator(f):
            self.add_event_handler(event_name, f, *args, **kwargs)
            return f
        return decorator