如何将句子插入到字符串中的特定位置？

def insert_sentence(original_str, sentence, index):
    # 将字符串切割为两部分
    part1 = original_str[:index]
    part2 = original_str[index:]
    
    # 使用字符串的拼接操作，将插入的句子与两部分重新组合成一个完整的字符串
    new_str = part1 + sentence + part2
    
    return new_str

original_str = "Hello, world!"
sentence = "inserted"
index = 7

new_str = insert_sentence(original_str, sentence, index)
print(new_str)

Hello, inserted world!