Validates a given value against this rule.

        :param path: a dot notation path to the value.

        :param schema: a schema this rule is called from

        :param value: a value to be validated.

        :param results: a list with validation results to add new results.

def validate(self, path, schema, value, results):
        """
        Validates a given value against this rule.

        :param path: a dot notation path to the value.

        :param schema: a schema this rule is called from

        :param value: a value to be validated.

        :param results: a list with validation results to add new results.
        """
        if self._rules == None:
            return

        for rule in self._rules:
            rule.validate(path, schema, value, results)