Generate a dummy airplane model.

        :param model_mask: Mask of truck model. Here '@' is a
            placeholder of characters and '#' is a placeholder of digits.
        :return: Airplane model.

        :Example:
            Boeing 727.

def airplane(self, model_mask: str = '###') -> str:
        """Generate a dummy airplane model.

        :param model_mask: Mask of truck model. Here '@' is a
            placeholder of characters and '#' is a placeholder of digits.
        :return: Airplane model.

        :Example:
            Boeing 727.
        """
        model = self.random.custom_code(mask=model_mask)
        plane = self.random.choice(AIRPLANES)
        return '{} {}'.format(plane, model)