function gsAPI($key = null, $secret = null)
 {
     if (!empty($key)) {
         self::$ws_key = $key;
     }
     if (!empty($secret)) {
         self::$ws_secret = $secret;
     }
     if (empty(self::$ws_key) || empty(self::$ws_secret)) {
         trigger_error("gsapi class requires a valid key and secret.", E_USER_ERROR);
     }
     if (!isset(self::$instance)) {
         self::$instance = $this;
     }
     self::$headers = array();
 }