static BWImage twoLevelIntListToBWImage(LL<Int> array) {
  if (empty(array)) null;
  int w = maxLength(array);
  int h = l(array);
  BWImage img = new(w, h);
  
  for y to h: {
    L<Int> row = array.get(y);
    for x to w: {
      Int value = get(row, x);
      if (value != null) 
        img.setInt(x, y, value);
    }
  }
  ret img;
}