如何从URL获取子域值？

from urllib.parse import urlparse

def get_subdomain_from_url(url):
    parsed_url = urlparse(url)
    hostname = parsed_url.hostname
    subdomains = hostname.split('.')
    if len(subdomains) > 2:
        return subdomains[:-2]  # 返回除顶级域名外的子域列表
    else:
        return None  # 没有子域

# 示例用法
url = "https://www.example.com"
subdomain = get_subdomain_from_url(url)
print(subdomain)  # 输出：['www']

url = "https://blog.example.com"
subdomain = get_subdomain_from_url(url)
print(subdomain)  # 输出：['blog']

url = "https://example.com"
subdomain = get_subdomain_from_url(url)
print(subdomain)  # 输出：None