private function makeRequest($http_verb, $method, $args = array(), $timeout = self::TIMEOUT)
    {
        $url = $this->api_endpoint . '/' . $method;

        $response = $this->prepareStateForRequest($http_verb, $method, $url, $timeout);

        $httpHeader = array(
            'Accept: application/vnd.api+json',
            'Content-Type: application/vnd.api+json',
            'Authorization: apikey ' . $this->api_key
        );

        if (isset($args["language"])) {
            $httpHeader[] = "Accept-Language: " . $args["language"];
        }

        if ($http_verb === 'put') {
            $httpHeader[] = 'Allow: PUT, PATCH, POST';
        }

        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $httpHeader);
        curl_setopt($ch, CURLOPT_USERAGENT, 'DrewM/MailChimp-API/3.0 (github.com/drewm/mailchimp-api)');
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_VERBOSE, true);
        curl_setopt($ch, CURLOPT_HEADER, true);
        curl_setopt($ch, CURLOPT_TIMEOUT, $timeout);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, $this->verify_ssl);
        curl_setopt($ch, CURLOPT_ENCODING, '');
        curl_setopt($ch, CURLINFO_HEADER_OUT, true);

        switch ($http_verb) {
            case 'post':
                curl_setopt($ch, CURLOPT_POST, true);
                $this->attachRequestPayload($ch, $args);
                break;

            case 'get':
                $query = http_build_query($args, '', '&');
                curl_setopt($ch, CURLOPT_URL, $url . '?' . $query);
                break;

            case 'delete':
                curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'DELETE');
                break;

            case 'patch':
                curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'PATCH');
                $this->attachRequestPayload($ch, $args);
                break;

            case 'put':
                curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'PUT');
                $this->attachRequestPayload($ch, $args);
                break;
        }

        $responseContent     = curl_exec($ch);
        $response['headers'] = curl_getinfo($ch);
        $response            = $this->setResponseState($response, $responseContent, $ch);
        $formattedResponse   = $this->formatResponse($response);

        curl_close($ch);

        $isSuccess = $this->determineSuccess($response, $formattedResponse, $timeout);

        return is_array($formattedResponse) ? $formattedResponse : $isSuccess;
    }