validator class

class Validator:
    def __call__(self, value):
        return self.validate(value)

class MinValidator(Validator):
    def __init__(self, minimum):
        self.minimum = minimum

    def validate(self, value):
        return value >= self.minimum

class MaxValidator(Validator):
    def __init__(self, maximum):
        self.maximum = maximum

    def validate(self, value):
        return value <= self.maximum

# big version
##class BetweenValidator(MinValidator, MaxValidator):
##    def __init__(self, minimum, maximum):
##        MinValidator.__init__(self, minimum)
##        MaxValidator.__init__(self, maximum)
##
##    def validate(self, value):
##        return MinValidator.validate(self, value) and MaxValidator.validate(self, value)

class MergeValidators(Validator):
    validator_classes = []

    def __init__(self, *args):
        for index, vclass in enumerate(self.validator_classes):
            if type(args[index]) == list:
                vclass.__init__(self, *args[index])
            else:
                vclass.__init__(self, args[index])

    def validate(self, value):
        for vclass in self.validator_classes:
            if not vclass.validate(self, value):
                return False

        return True

# small version
class BetweenValidator(MergeValidators):
    validator_classes = [
        MinValidator,
        MaxValidator
    ]

assert BetweenValidator(18, 25)(18)
# same as "MinValidator(18)(18) and MaxValidator(25)(18)"