src/vs/base/common/strings.ts/AmbiguousCharacters/mergeMaps
class AmbiguousCharacters:		function mergeMaps(
			map1: Map<number, number>,
			map2: Map<number, number>
		): Map<number, number> {
			const result = new Map<number, number>(map1);
			for (const [key, value] of map2) {
				result.set(key, value);
			}
			return result;
		}