code: def just_find_proxy(pacfile, url, host=None):
    
    if not os.path.isfile(pacfile):
      raise IOError('Pac file does not exist: {}'.format(pacfile))
    init()
    parse_pac(pacfile)
    proxy = find_proxy(url,host)
    cleanup()
    return proxy
docs: This function is a wrapper around init, parse_pac, find_proxy
    and cleanup. This is the function to call if you want to find
    proxy just for one url.