code: def draw_mask(im, mask, alpha=0.5, color=None):
      
      if color is None:
          color = PALETTE_RGB[np.random.choice(len(PALETTE_RGB))][::-1]
      im = np.where(np.repeat((mask > 0)[:, :, None], 3, axis=2),
                    im * (1 - alpha) + color * alpha, im)
      im = im.astype('uint8')
      return im
docs: Overlay a mask on top of the image.
  
      Args:
          im: a 3-channel uint8 image in BGR
          mask: a binary 1-channel image of the same size
          color: if None, will choose automatically