build/lib/i18n.ts/is
	export function is(value: any): value is BundledFormat {
		if (Is.undef(value)) {
			return false;
		}

		let candidate = value as BundledFormat;
		let length = Object.keys(value).length;

		return length === 3 && Is.defined(candidate.keys) && Is.defined(candidate.messages) && Is.defined(candidate.bundles);
	}