Aerys\CommandClient::send PHP Method

    private function send($msg) : \Amp\Promise
    {
        if (!$this->sock) {
            $this->establish();
        } elseif (!$this->writeWatcher) {
            $this->writeWatcher = \Amp\onWritable($this->sock, $this->writer);
        }
        $msg = json_encode($msg);
        $this->buf .= pack("N", \strlen($msg)) . $msg;
        return ($this->promisors[\strlen($this->buf)] = new \Amp\Deferred())->promise();
    }