code: func (e *Entry) execPrefix(method, urlStr string) (*Route, []string) {
  	if !strings.HasPrefix(urlStr, e.pattern) {
  		return nil, nil
  	}
  	if len(urlStr) == len(e.pattern) {
  		return e.GetHandler(method), nil
  	}
  	return e.traverse(method, urlStr[len(e.pattern):])
  }
docs: // execPrefix simply see if the given urlStr has a leading pattern.