from zlib_dl import ZLibSession
import re
from bs4 import BeautifulSoup
s = ZLibSession(verbose=True)
url = "https://zlib.li/book/mDJxkg7yO6/%E6%B5%AA%E6%BD%AE%E4%B9%8B%E5%B7%85%E7%AC%AC%E5%9B%9B%E7%89%88.html"
resp = s._request_download(url)
soup = BeautifulSoup(resp.text, 'html.parser')
a_tag = soup.find('a', href=re.compile(r"^/dl/\w+"))
if a_tag:
    print(f"FOUND: {a_tag['href']}")
else:
    print("NOT FOUND")
    # let's try another heuristic
    dl_btn = soup.find('a', class_=re.compile(r"addDownloadedBook"))
    if dl_btn:
        print("FOUND VIA CLASS:", dl_btn.get("href"))
    else:
        print("STILL NOT FOUND")