code: protected function runExtension(/*# string */ $method, array $args)
      {
          /* @var $ext ExtensionInterface */
          $ext = $this->extension_methods[$method];
  
          // execute extesion method
          return call_user_func_array([$ext, $method], $args);
      }
docs: Include this in server's __call()
  
  @param  string $method
  @param  array $args
  @return mixed
  @access protected