def remove_subset(ls: list) ->list:
    """去除列表中的子集。比如：['aa','a','ab'] --> ['aa','ab']"""
    ls.sort(key=lambda x: len(x[0]), reverse=True)
    total = []
    for subset in ls:
        flag = True
        for word in total:
            if subset[0] in word[0]:
                flag = False
                break
        if flag:
            total.append(subset)
    return total
