使用值为字符串的python排序json文件

i have json file:

我有json文件：

ll = {"employees":[
    {"firstName":"John", "lastName":"Doe"},
    {"firstName":"Anna", "lastName":"Smith"},
    {"firstName":"James", "lastName":"Bond"},
    {"firstName":"Celestial", "lastName":"Systems"},
    {"firstName":"Peter", "lastName":"Jones"}
]}
ll = {"employee