'Start sending some pings.
:param AMP protocol: The protocol over which to send the pings.
:param timedelta interval: The interval at which to send the pings.'

def start(self, protocol, interval):

    def ping():
        protocol.callRemote(NoOp)
    self._pinging = LoopingCall(ping)
    self._pinging.clock = self.reactor
    self._pinging.start(interval.total_seconds(), now=False)
