How to use the podcastparser.parse_date function in podcastparser

def get_metadata(url):
    """Get file download metadata

    Returns a (size, type, name) from the given download
    URL. Will use the network connection to determine the
    metadata via the HTTP header fields.
    """
    track_fp = util.urlopen(url)
    headers = track_fp.info()
    filesize = headers['content-length'] or '0'
    filetype = headers['content-type'] or 'application/octet-stream'

    if 'last-modified' in headers:
        filedate = podcastparser.parse_date(headers['last-modified'])
    else:
        filedate = None

    filename = os.path.basename(os.path.dirname(url))
    track_fp.close()
    return filesize, filetype, filedate, filename