code: func (a *Args) GetUfloat(key string) (float64, error) {
  	value := a.Peek(key)
  	if len(value) == 0 {
  		return -1, ErrNoArgValue
  	}
  	return ParseUfloat(value)
  }
docs: // GetUfloat returns ufloat value for the given key.