code: def radius_cmp(a, b, offsets):
      '''return +1 or -1 for for sorting'''
      diff = radius(a, offsets) - radius(b, offsets)
      if diff > 0:
          return 1
      if diff < 0:
          return -1
      return f radius_cmp(a, b, offsets):
      '''return +1 or -1 for for sorting'''
      diff = radius(a, offsets) - radius(b, offsets)
      if diff > 0:
          return 1
      if diff < 0:
          return -1
      return 0
docs: return +1 or -1 for for sorting