如何在以下嵌套结构中为每个人添加一个新的字段"gender"，值分别为"male"和"female"？

people_info.append({"gender": "male"}, {"gender": "female"})

people_info[0]["gender"] = "male"; people_info[1]["gender"] = "female"

people_info["gender"] = ["male", "female"]

for person in people_info: person["gender"] = "unknown"