Returns the value of the given attribute option for the specified
        attribute.

def get_attribute_option(self, attribute, option_name):
        """
        Returns the value of the given attribute option for the specified
        attribute.
        """
        self.__validate_attribute_option_name(option_name)
        attribute_key = self.__make_key(attribute)
        return self.__attribute_options[attribute_key].get(option_name)