code: def pad_decr(ids):
    
    if len(ids) < 1:
      return list(ids)
    if not any(ids):
      return []  # all padding.
    idx = -1
    while not ids[idx]:
      idx -= 1
    if idx == -1:
      ids = ids
    else:
      ids = ids[:idx + 1]
    return [i - 1 for i in ids]
docs: Strip ID 0 and decrement ids by 1.