code: def hue(self, color, *args):
          
          if color:
              h, l, s = self._hextohls(color)
              return utility.convergent_round(h * 360.0, 3)
          raise ValueError('Illegal color values')
docs: Return the hue value of a color
          args:
              color (str): color
          raises:
              ValueError
          returns:
              float