Simple requests and beautiful soup example

scrape.py

import sys

import requests
from bs4 import BeautifulSoup

def download_html(url: str, filename: str):
    r = requests.get(url)
    r.raise_for_status()
    
    html = r.text
    soup = BeautifulSoup(html, 'html.parser')
    html = soup.prettify()
    
    with open(filename, 'w') as f:
        f.write(html)

if __name__ == '__main__':
    n_args = len(sys.argv) - 1
    
    if (n_args < 1) or (n_args > 3):
        raise ValueError('Invalid arguments, use: python scraper.py url output.html')
    
    url = sys.argv[1]
    
    if n_args == 1:
        download_html(url, 'website.html')
    else:
        filename = sys.argv[2]
        download_html(url, filename)