src/vs/workbench/api/common/extHostComments.ts/ExtHostCommentsImpl/$provideCommentingRanges
class ExtHostCommentsImpl:		$provideCommentingRanges(commentControllerHandle: number, uriComponents: UriComponents, token: CancellationToken): Promise<IRange[] | undefined> {
			const commentController = this._commentControllers.get(commentControllerHandle);

			if (!commentController || !commentController.commentingRangeProvider) {
				return Promise.resolve(undefined);
			}

			const document = documents.getDocument(URI.revive(uriComponents));
			return asPromise(() => {
				return commentController.commentingRangeProvider!.provideCommentingRanges(document, token);
			}).then(ranges => ranges ? ranges.map(x => extHostTypeConverter.Range.from(x)) : undefined);
		}