src/vs/workbench/services/search/common/fileSearchManager.ts/FileSearchManager/getSessionTokenSource
class FileSearchManager:	private getSessionTokenSource(cacheKey: string | undefined): CancellationTokenSource | undefined {
		if (!cacheKey) {
			return undefined;
		}

		if (!this.sessions.has(cacheKey)) {
			this.sessions.set(cacheKey, new CancellationTokenSource());
		}

		return this.sessions.get(cacheKey);
	}