code: func ParseBool(q url.Values, name string) (bool, bool, error) {
  	stringVal := q.Get(name)
  	if stringVal == "" {
  		return false, false, nil
  	}
  
  	val, err := strconv.ParseBool(stringVal)
  	if err != nil {
  		return false, false, trace.BadParameter(
  			"'%v': expected 'true' or 'false', got %v", name, stringVal)
  	}
  	return val, true, nil
  }
docs: // ParseBool will parse boolean variable from url query
  // returns value, ok, error