code: func heartbeatHandler(timer *time.Timer) func(*ecstcs.HeartbeatMessage) {
  	return func(*ecstcs.HeartbeatMessage) {
  		seelog.Debug("Received HeartbeatMessage from tcs")
  		timer.Reset(retry.AddJitter(defaultHeartbeatTimeout, defaultHeartbeatJitter))
  	}
  }
docs: // heartbeatHandler resets the heartbeat timer when HeartbeatMessage message is received from tcs.