How to use the aniso8601.resolution.DateResolution.Week function in aniso8601

#YYYYWwwD
    #YYYY-DDD
    #YYYYDDD
    if isodatestr.startswith('+') or isodatestr.startswith('-'):
        raise NotImplementedError('ISO 8601 extended year representation not supported.')
    isodatestrlen = len(isodatestr)

    if isodatestr.find('W') != -1:
        #Handle ISO 8601 week date format
        hyphens_present = 1 if isodatestr.find('-') != -1 else 0
        week_date_len = 7 + hyphens_present
        weekday_date_len = 8 + 2*hyphens_present
        if isodatestrlen == week_date_len:
            #YYYY-Www
            #YYYYWww
            return DateResolution.Week
        elif isodatestrlen == weekday_date_len:
            #YYYY-Www-D
            #YYYYWwwD
            return DateResolution.Weekday
        else:
            raise ValueError('String is not a valid ISO 8601 week date.')

    #If the size of the string of 4 or less, assume its a truncated year representation
    if len(isodatestr) <= 4:
        return DateResolution.Year

    #An ISO string may be a calendar represntation if:
    # 1) When split on a hyphen, the sizes of the parts are 4, 2, 2 or 4, 2
    # 2) There are no hyphens, and the length is 8
    datestrsplit = isodatestr.split('-')