import requests
from lxml import etree as ET

def download_feed(s, url, file, remove_premium=False, fulltext=False):
    r = s.get(url)
    tree = ET.ElementTree(ET.fromstring(r.text))
    root = tree.getroot()
    for post in tree.iter('item'):
        if remove_premium and "[$]" in post.find('title').text:
            root[0].remove(post)
        ## TODO: full-text parsing

    tree.write(file)

s = requests.Session()
s.headers.update({'User-Agent': 'FreshRSS/1.23.1 (Linux; https://freshrss.org)'})

download_feed(s, "https://lwn.net/headlines/Features", "lwn-features.xml", remove_premium=True)
download_feed(s, "https://lwn.net/headlines/rss", "lwn-all.xml", remove_premium=True)