function list(options, fallback = options[0]) {
	return validator(fallback, (input, keypath) => {
		if (!options.includes(input)) {
			// prettier-ignore
			const msg = options.length > 2
				? `${keypath} should be one of ${options.slice(0, -1).map(input => `"${input}"`).join(', ')} or "${options[options.length - 1]}"`
				: `${keypath} should be either "${options[0]}" or "${options[1]}"`;

			throw_error(msg);
		}
		return input;
	});
}
@param {Array<boolean | string | number>} options
@returns {Validator}