python提取json字符串的值

json_str={
    "actor":"邓超",
    "age":35,
    "book":[
        "英语",
        "数学",
        "美术"
    ],
    "children":[
        {
            "name":"等等",
            "age":7,
            "sex":"male"
        },
        {
            "name":"花花",
            "age":3,
            "sex":"female"
        }
    ]
}



#获取actor 的值
actor=json_str['actor']
#获取 book 的第二个值
book_2=json_str['book'][1]
#获取第二个孩子的性别
sex2=json_str['children'][1]['sex']