Amp\Artax\Client::writeRequest PHP Method

    private function writeRequest(RequestCycle $cycle)
    {
        $rawHeaders = $this->generateRawRequestHeaders($cycle->request);
        $writePromise = (new BufferWriter())->write($cycle->socket, $rawHeaders);
        $writePromise->watch(function ($update) use($cycle) {
            $cycle->futureResponse->update([Notify::SOCK_DATA_OUT, $update]);
            if ($cycle->options[self::OP_VERBOSITY] & self::VERBOSE_SEND) {
                echo $update;
            }
        });
        $writePromise->when(function ($error, $response) use($cycle) {
            if ($error) {
                $this->fail($cycle, $error);
            } else {
                $this->afterHeaderWrite($cycle);
            }
        });
    }