如何用带有随机ASCII字符的字符串替换多次出现的字符？

def replace_chars_with_random_string(string, char):
    # 实现替换逻辑的代码
    pass

def replace_chars_with_random_string(string, char):
    new_string = ""
    for c in string:
        if c == char:
            # 需要替换的字符
            # 生成随机ASCII字符的代码
            # 将随机字符添加到新字符串中
        else:
            # 不需要替换的字符
            # 直接将字符添加到新字符串中
    return new_string

import random
import string

def replace_chars_with_random_string(string, char):
    new_string = ""
    for c in string:
        if c == char:
            random_char = random.choice(string.ascii_letters + string.digits + string.punctuation)
            new_string += random_char
        else:
            new_string += c
    return new_string

original_string = "This is a test string."
replacement_char = "s"
new_string = replace_chars_with_random_string(original_string, replacement_char)
print(new_string)