53-集合的使用：取出差异的内容

with open('./passwd') as fobj:
    aset = set(fobj)
    print(aset)

with open('./mima') as fobj:
    bset = set(fobj)
    print(bset)

with open('diff.txt', 'w') as fobj:
    fobj.writelines(aset - bset)

结果输出：