import requests


def _check_url(url):
    """Checks if a url is alive
    
    Arguments:
        url str -- url to check
    
    Returns:
        bool -- True if url exists
    """
    r = requests.head(url)
    # If repo is private, it will return 401 for issue links,
    # we can't fully check if the issue exists or not then though.
    return r.status_code == 200 or r.status_code == 401