code: def saturation(p):
      
      max_c = max(p)
      min_c = min(p)
      if max_c == 0:
          return 0
      return (max_c - min_c) / float(max_c)
docs: Returns the saturation of a pixel, defined as the ratio of chroma to value.
      :param p: A tuple of (R,G,B) values
      :return: The saturation of a pixel, from 0 to 1