function generateUUID() {

	// http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript/21963136#21963136

	const d0 = Math.random() * 0xffffffff | 0;
	const d1 = Math.random() * 0xffffffff | 0;
	const d2 = Math.random() * 0xffffffff | 0;
	const d3 = Math.random() * 0xffffffff | 0;
	const uuid = _lut[ d0 & 0xff ] + _lut[ d0 >> 8 & 0xff ] + _lut[ d0 >> 16 & 0xff ] + _lut[ d0 >> 24 & 0xff ] + '-' +
			_lut[ d1 & 0xff ] + _lut[ d1 >> 8 & 0xff ] + '-' + _lut[ d1 >> 16 & 0x0f | 0x40 ] + _lut[ d1 >> 24 & 0xff ] + '-' +
			_lut[ d2 & 0x3f | 0x80 ] + _lut[ d2 >> 8 & 0xff ] + '-' + _lut[ d2 >> 16 & 0xff ] + _lut[ d2 >> 24 & 0xff ] +
			_lut[ d3 & 0xff ] + _lut[ d3 >> 8 & 0xff ] + _lut[ d3 >> 16 & 0xff ] + _lut[ d3 >> 24 & 0xff ];

	// .toLowerCase() here flattens concatenated strings to save heap memory space.
	return uuid.toLowerCase();

}
Generate a [UUID]{@link https://en.wikipedia.org/wiki/Universally_unique_identifier}
(universally unique identifier).

@return {string} The UUID.