src/vs/workbench/contrib/welcomeGettingStarted/browser/gettingStartedService.ts/WalkthroughsService/getWalkthrough
class WalkthroughsService:	getWalkthrough(id: string): IResolvedWalkthrough {
		const walkthrough = this.gettingStartedContributions.get(id);
		if (!walkthrough) { throw Error('Trying to get unknown walkthrough: ' + id); }
		return this.resolveWalkthrough(walkthrough);
	}