How to use the yamale.validators.constraints.Constraint function in yamale

raise SyntaxError('%s is not a %s' % (key, kwtype))

    def is_valid(self, value):
        if not self.is_active:
            return None

        if not self._is_valid(value):
            return self._fail(value)

        return None

    def _fail(self, value):
        return '\'%s\' violates %s.' % (value, self.__class__.__name__)


class Min(Constraint):
    fail = '%s is less than %s'

    def __init__(self, value_type, kwargs):
        self.keywords = {'min': value_type}
        super(Min, self).__init__(value_type, kwargs)

    def _is_valid(self, value):
        return self.min <= value

    def _fail(self, value):
        return self.fail % (value, self.min)


class Max(Constraint):
    fail = '%s is greater than %s'

def _fail(self, value):
        return self.fail % (value, self.min)


class LengthMax(Constraint):
    keywords = {'max': int}
    fail = 'Length of %s is greater than %s'

    def _is_valid(self, value):
        return self.max >= len(value)

    def _fail(self, value):
        return self.fail % (value, self.max)


class CharacterExclude(Constraint):
    keywords = {'exclude': str}
    fail = '\'%s\' contains excluded character \'%s\''

    def _is_valid(self, value):
        for char in self.exclude:
            if char in value:
                self._failed_char = char
                return False
        return True

    def _fail(self, value):
        return self.fail % (value, self._failed_char)


class IpVersion(Constraint):
    keywords = {'version': int}

class Max(Constraint):
    fail = '%s is greater than %s'

    def __init__(self, value_type, kwargs):
        self.keywords = {'max': value_type}
        super(Max, self).__init__(value_type, kwargs)

    def _is_valid(self, value):
        return self.max >= value

    def _fail(self, value):
        return self.fail % (value, self.max)


class LengthMin(Constraint):
    keywords = {'min': int}
    fail = 'Length of %s is less than %s'

    def _is_valid(self, value):
        return self.min <= len(value)

    def _fail(self, value):
        return self.fail % (value, self.min)


class LengthMax(Constraint):
    keywords = {'max': int}
    fail = 'Length of %s is greater than %s'

    def _is_valid(self, value):
        return self.max >= len(value)

class CharacterExclude(Constraint):
    keywords = {'exclude': str}
    fail = '\'%s\' contains excluded character \'%s\''

    def _is_valid(self, value):
        for char in self.exclude:
            if char in value:
                self._failed_char = char
                return False
        return True

    def _fail(self, value):
        return self.fail % (value, self._failed_char)


class IpVersion(Constraint):
    keywords = {'version': int}
    fail = 'IP version of %s is not %s'

    def _is_valid(self, value):
        try:
            import ipaddress
        except ImportError:
            raise ImportError("You must install the ipaddress backport in Py2")
        try:
            ip = ipaddress.ip_interface(to_unicode(value))
        except ValueError:
            return False
        return self.version == ip.version

    def _fail(self, value):
        return self.fail % (value, self.version)

def _fail(self, value):
        return self.fail % (value, self.max)


class LengthMin(Constraint):
    keywords = {'min': int}
    fail = 'Length of %s is less than %s'

    def _is_valid(self, value):
        return self.min <= len(value)

    def _fail(self, value):
        return self.fail % (value, self.min)


class LengthMax(Constraint):
    keywords = {'max': int}
    fail = 'Length of %s is greater than %s'

    def _is_valid(self, value):
        return self.max >= len(value)

    def _fail(self, value):
        return self.fail % (value, self.max)


class CharacterExclude(Constraint):
    keywords = {'exclude': str}
    fail = '\'%s\' contains excluded character \'%s\''

    def _is_valid(self, value):
        for char in self.exclude:

class Min(Constraint):
    fail = '%s is less than %s'

    def __init__(self, value_type, kwargs):
        self.keywords = {'min': value_type}
        super(Min, self).__init__(value_type, kwargs)

    def _is_valid(self, value):
        return self.min <= value

    def _fail(self, value):
        return self.fail % (value, self.min)


class Max(Constraint):
    fail = '%s is greater than %s'

    def __init__(self, value_type, kwargs):
        self.keywords = {'max': value_type}
        super(Max, self).__init__(value_type, kwargs)

    def _is_valid(self, value):
        return self.max >= value

    def _fail(self, value):
        return self.fail % (value, self.max)


class LengthMin(Constraint):
    keywords = {'min': int}
    fail = 'Length of %s is less than %s'