OAuth2\HttpClient::execute PHP Method

    public function execute()
    {
        $ch = curl_init();
        if ($this->_method === 'POST') {
            curl_setopt($ch, CURLOPT_URL, $this->_url);
            curl_setopt($ch, CURLOPT_POST, 1);
            curl_setopt($ch, CURLOPT_POSTFIELDS, $this->_parameters);
        } else {
            curl_setopt($ch, CURLOPT_URL, $this->_url . ($this->_parameters ? '?' . $this->_parameters : ''));
        }
        curl_setopt($ch, CURLOPT_HEADER, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        if (!empty($this->_requestHeader)) {
            curl_setopt($ch, CURLOPT_HTTPHEADER, $this->_requestHeader);
        }
        $fullResponse = curl_exec($ch);
        $this->_info = curl_getinfo($ch);
        $this->_response = substr($fullResponse, $this->_info['header_size'], strlen($fullResponse));
        if ($this->_response === false) {
            $this->_response = '';
        }
        $headers = rtrim(substr($fullResponse, 0, $this->_info['header_size']));
        $this->_headers = static::parseStringToArray($headers, PHP_EOL, ':');
        if ($this->_debug) {
            echo "<pre>";
            print_r($this->_url);
            echo PHP_EOL;
            print_r($this->_headers);
            echo PHP_EOL;
            print_r($this->_response);
            echo "</pre>";
        }
        curl_close($ch);
    }