src/vs/workbench/contrib/files/common/explorerFileNestingTrie.ts/SufTrie/add
class SufTrie:	add(key: string, value: string) {
		this.hasItems = true;
		if (key === '*') {
			this.star.push(new SubstitutionString(value));
		} else if (key === '') {
			this.epsilon.push(new SubstitutionString(value));
		} else {
			const tail = key[key.length - 1];
			const rest = key.slice(0, key.length - 1);
			if (tail === '*') {
				throw Error('Unexpected star in SufTrie key: ' + key);
			} else {
				let existing = this.map.get(tail);
				if (!existing) {
					this.map.set(tail, existing = new SufTrie());
				}
				existing.add(rest, value);
			}
		}
	}