docs: def neighbors((x, y)):
      """Return the (possibly out of bounds) neighbors of a point."""
      yield x + 1, y
      yield x - 1, y
      yield x, y + 1
      yield x, y - 1
      yield x + 1, y + 1
      yield x + 1, y - 1
      yield x - 1, y + 1
      yield x - 1, y - 1