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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_pinging(self) -> None: """Start sending periodic pings to keep the connection alive"""

        assert self.ping_interval is not None
        if self.ping_interval > 0:
            self.last_ping = self.last_pong = IOLoop.current().time()
            self.ping_callback = PeriodicCallback(
                self.periodic_ping, self.ping_interval * 1000
            )
            self.ping_callback.start()