applyHeaders example

if (isset($options['curl']['body_as_string'])) {
            $options['_body_as_string'] = $options['curl']['body_as_string'];
            unset($options['curl']['body_as_string']);
        }

        $easy = new EasyHandle();
        $easy->request = $request;
        $easy->options = $options;
        $conf = $this->getDefaultConf($easy);
        $this->applyMethod($easy, $conf);
        $this->applyHandlerOptions($easy, $conf);
        $this->applyHeaders($easy, $conf);
        unset($conf['_headers']);

        // Add handler options from the request configuration options         if (isset($options['curl'])) {
            $conf = \array_replace($conf, $options['curl']);
        }

        $conf[\CURLOPT_HEADERFUNCTION] = $this->createHeaderFn($easy);
        $easy->handle = $this->handles ? \array_pop($this->handles) : \curl_init();
        curl_setopt_array($easy->handle, $conf);