def map_age(age):
        """ Map age to correct age-group. """

        if age in [None, '']:
            return issuers.AgeGroup.UNKNOWN
        elif age == 'teens':
            return issuers.AgeGroup.YOUTH
        elif age in ['sixties', 'seventies', 'eighties', 'nineties']:
            return issuers.AgeGroup.SENIOR
        else:
            return issuers.AgeGroup.ADULT
Map age to correct age-group.