【python】～webサイト上のpdfを一括ダウンロードする～

from bs4 import BeautifulSoup
import os
import requests
import time
import sys

args = sys.argv

if len(args) < 2:
    print("Arguments are too short")
    sys.exit()


download_urls = []
BASE_URL = args[1].rsplit('/', 1)[0] + '/'

if os.path.exists("tmp_folder") == False:
    os.mkdir("tmp_folder")
    
html = requests.get(args[1])

soup = BeautifulSoup(html.text, "lxml")
links = soup.find_all("a")

for link in links:
    h_ref = link.get("href")
    
    if h_ref and ".pdf" in h_ref:
        download_urls.append(h_ref)
        
for download_url in download_urls:
    file_name = download_url.split("/")[-1]
    r = requests.get(BASE_URL + download_url)
    time.sleep(1)
    
    if r.status_code == 200:
        with open(os.path.join("tmp_folder", file_name), "wb") as f:
            f.write(r.content)

$python pdf_dl.py "pdfをダウンロードしたいサイトのURL"