docs: def pick_orientation(img1, img2, spacing, desired_aspect=1.618):
      """Pick a tiling orientation for two images.
  
      Returns either 'lr' for left-and-right, or 'tb' for top-and-bottom.
  
      Picks the one that makes the combined image have a better aspect
      ratio, where 'better' is defined as 'closer to 1:1.618'.
      """
      w1, h1 = img1.size
      w2, h2 = img2.size
  
      size_a = (w1 + spacing + w2, max(h1, h2, 1))
      size_b = (max(w1, w2, 1), h1 + spacing + h2)
  
      aspect_a = size_a[0] / size_a[1]
      aspect_b = size_b[0] / size_b[1]
  
      goodness_a = min(desired_aspect, aspect_a) / max(desired_aspect, aspect_a)
      goodness_b = min(desired_aspect, aspect_b) / max(desired_aspect, aspect_b)
  
      return 'lr' if goodness_a >= goodness_b else 'tb'