Check if a URL is valid and points to a live site or not.

url_check.py

def valid_url(url):
    if (url.lower() == 'none') or (url == ''):
        return False
    try:
        s = requests.Session()
        a = requests.adapters.HTTPAdapter(max_retries=5)
        s.mount(url, a)
        resp = s.head(url)
        return resp.ok
    except requests.exceptions.MissingSchema:
        # If it's missing the schema, run again with schema added
        return valid_url('http://' + url)
    except requests.exceptions.ConnectionError:
        print('Error trying to connect to {}.'.format(url))
        return False