How to use the crontab.crontab.CronValue function in crontab

def get_cronvalue(value, enums):
    """Returns a value as int (pass-through) or a special enum value"""
    if isinstance(value, int):
        return value
    elif str(value).isdigit():
        return int(str(value))
    if not enums:
        raise KeyError("No enumeration allowed")
    return CronValue(str(value), enums)

def __init__(self, vslice, *vrange):
        # holds an extra dangling entry, for example sundays.
        self.dangling = None
        self.slice = vslice
        self.cron = None
        self.seq = 1

        if not vrange:
            self.all()
        elif isinstance(vrange[0], basestring):
            self.parse(vrange[0])
        elif isinstance(vrange[0], int) or isinstance(vrange[0], CronValue):
            if len(vrange) == 2:
                (self.vfrom, self.vto) = vrange
            else:
                self.seq = vrange[0]
                self.all()