src/vs/workbench/contrib/files/common/explorerFileNestingTrie.ts/SufTrie/toString
class SufTrie:	toString(indentation = ''): string {
		const lines = [];
		if (this.star.length) {
			lines.push('* => ' + this.star.join('; '));
		}

		if (this.epsilon.length) {
			// allow-any-unicode-next-line
			lines.push('ε => ' + this.epsilon.join('; '));
		}

		[...this.map.entries()].map(([key, trie]) =>
			lines.push(key + '$' + ' => \n' + trie.toString(indentation + '  ')));

		return lines.map(l => indentation + l).join('\n');
	}