docs: def next_color(self):
          """
          Returns the next color. Currently returns a random
          color from the Colorbrewer 11-class diverging BrBG palette.
  
          Returns
          -------
          next_rgb_color: tuple of ImageColor
  
          """
          next_rgb_color = ImageColor.getrgb(random.choice(BrBG_11.hex_colors))
          return next_rgb_color