private function sendHeartbeatPing(Rfc6455Client $client)
{
if ($client->pingCount - $client->pongCount > $this->queuedPingLimit) {
$code = Code::POLICY_VIOLATION;
$reason = 'Exceeded unanswered PING limit';
$this->doClose($client, $code, $reason);
} else {
$this->compile($client, $client->pingCount++, self::OP_PING);
}
}