React\HttpClient\Request::writeHead PHP Method

    public function writeHead()
    {
        if (self::STATE_WRITING_HEAD <= $this->state) {
            throw new \LogicException('Headers already written');
        }
        $this->state = self::STATE_WRITING_HEAD;
        $requestData = $this->requestData;
        $streamRef =& $this->stream;
        $stateRef =& $this->state;
        $this->connect()->done(function ($stream) use($requestData, &$streamRef, &$stateRef) {
            $streamRef = $stream;
            $stream->on('drain', array($this, 'handleDrain'));
            $stream->on('data', array($this, 'handleData'));
            $stream->on('end', array($this, 'handleEnd'));
            $stream->on('error', array($this, 'handleError'));
            $headers = (string) $requestData;
            $stream->write($headers);
            $stateRef = Request::STATE_HEAD_WRITTEN;
            $this->emit('headers-written', array($this));
        }, array($this, 'handleError'));
    }