def clean(self, value):
        value = super(ITSocialSecurityNumberField, self).clean(value)
        if value in EMPTY_VALUES:
            return ''
        value = re.sub('\s', '', value).upper()
        try:
            check_digit = ssn_check_digit(value)
        except __HOLE__:
            raise ValidationError(self.error_messages['invalid'])
        if not value[15] == check_digit:
            raise ValidationError(self.error_messages['invalid'])
        return value
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/contrib/localflavor/it/forms.py/ITSocialSecurityNumberField.clean