code: def color_cmp(a, b):
      
      if a == b:
          return 0
  
      a, b = rgb_to_hsv(a), rgb_to_hsv(b)
      return -1 if a < b else 1
docs: Order colors by hue, saturation and value, in that order.
  
      Returns -1 if a < b, 0 if a == b and 1 if a < b.