code: def scale(self, new_max_value=1):
          
          f = new_max_value / self.max
          return ColorRGB(self.r * f,
                          self.g * f,
                          self.b * f,
                          max_value=new_max_value)
docs: Scale R, G and B parameters
          :param new_max_value: how much to scale
          :return: a new ColorRGB instance