code: public function getOption($key)
      {
          if (!array_key_exists($key, self::$options)) {
              // if a default has been defined
              if (func_num_args() > 1) {
                  return func_get_arg(1);
              } else {
                  throw new InternalException('Option "'.$key.'" has not been set');
              }
          }
          return self::$options[$key];
      }
docs: Get option
  
  @param string $key - option key
  
  @return mixed option