private static function curl(string $endpoint)
    {
        // Get the base URL and App Key.
        $baseUrl = self::$_baseUrl;

        // Create a cURL session.
        $curl = curl_init();

        // Set the options necessary for communicating with the UCRM Server.
        curl_setopt($curl, CURLOPT_URL, $baseUrl.$endpoint);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($curl, CURLOPT_HEADER, false);

        // TODO: Determine if we EVER need to use HTTPS and how to handle it correctly here!
        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 2); // DEFAULT
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, 1); // DEFAULT

        // Set the necessary HTTP HEADERS.
        curl_setopt($curl, CURLOPT_HTTPHEADER, self::$_headers);

        return $curl;
    }