Extract date from URL page if exists.

def find_date(url):
    "Extract date from URL page if exists."
    def _clean_split(div_str):
        sl = []
        for div in div_str.split('/'):
            div = div.strip().lower()
            if div != '':
                sl.append(div)
        return sl
        
    url_path = find_path(url)
    url_path_parts = _clean_split(url_path)
    date_parts = []
    for part in url_path_parts:
        try:
            _dateparse(part) # is part date-like?
            date_parts.append(part)
        except ValueError:
            continue
    if len(date_parts) == 0:
        return
    date_str = '/'.join(date_parts)
    return _dateparse(date_str)