protected function buildProxy()
    {
        if (isset($this->proxy['host'])) {
            $uri = new Uri([
                'scheme' => 'tcp',
                'host'   => $this->proxy['host'],
                'port'   => isset($this->proxy['port']) ? $this->proxy['port'] : 80,
            ]);

            if (isset($this->proxy['access'])) {
                $uri->user = $this->proxy['access'];
            }

            $this->setOption('proxy', $uri->build());
        }

        return $this;
    }