src/vs/workbench/contrib/notebook/common/notebookCommon.ts/parseCellUri
	export function parseCellUri(metadata: URI, scheme: string) {
		if (metadata.scheme !== scheme) {
			return undefined;
		}
		const match = _regex.exec(metadata.fragment);
		if (!match) {
			return undefined;
		}
		const handle = Number(match[1]);
		return {
			handle,
			notebook: metadata.with({
				scheme: metadata.fragment.substring(match[0].length) || Schemas.file,
				fragment: null
			})
		};
	}