如何用正则表达式检查url是否包含WWW？

^(https?://)?(www\.)?[a-zA-Z0-9-]+\.[a-zA-Z]{2,}(/\S*)?$

import re

def check_url_contains_www(url):
    pattern = r'^(https?://)?(www\.)?[a-zA-Z0-9-]+\.[a-zA-Z]{2,}(/\S*)?$'
    match = re.search(pattern, url)
    if match:
        return True
    else:
        return False

# 示例用法
url1 = 'https://www.example.com'
url2 = 'http://example.com'
url3 = 'www.example.com'

print(check_url_contains_www(url1))  # True
print(check_url_contains_www(url2))  # False
print(check_url_contains_www(url3))  # True