在文本文件中，如何删除紧跟其后一行的所有行子集？

def delete_subset_lines(filename):
    with open(filename, 'r') as file:
        lines = file.readlines()

    new_lines = []
    i = 0
    while i < len(lines):
        current_line = lines[i].strip()
        next_line = lines[i+1].strip() if i+1 < len(lines) else None

        if next_line and next_line.startswith(current_line):
            # 删除当前行及其子集行
            i += 1
            while i < len(lines) and lines[i].strip().startswith(current_line):
                i += 1
        else:
            new_lines.append(lines[i])
            i += 1

    with open(filename, 'w') as file:
        file.writelines(new_lines)

# 使用示例
delete_subset_lines('example.txt')