运行这段Python代码，字典会变成什么样子？（ ）
cat = {'三花猫':7, '布偶猫':11, '狸花猫':13} cat['三花猫'] = 5
{'三花猫':7, '布偶猫':11, '狸花猫':13}
{'三花猫':5, '布偶猫':11, '狸花猫':13}
{'三花猫':5, '三花猫':7 ,'布偶猫':11, '狸花猫':13}
程序会报错
