如何替换精确的字符串

import re

def replace_exact_string(target_string, search_string, replace_string):
    # 使用正则表达式进行精确匹配
    pattern = r'\b' + re.escape(search_string) + r'\b'
    replaced_string = re.sub(pattern, replace_string, target_string)
    return replaced_string

# 示例用法
target_string = "This is a test string. Test is a keyword."
search_string = "Test"
replace_string = "Replacement"
replaced_string = replace_exact_string(target_string, search_string, replace_string)
print(replaced_string)