src/vs/workbench/contrib/notebook/common/notebookCommon.ts/NotebookWorkingCopyTypeIdentifier/parse
class NotebookWorkingCopyTypeIdentifier:	static parse(candidate: string): string | undefined {
		if (candidate.startsWith(NotebookWorkingCopyTypeIdentifier._prefix)) {
			return candidate.substr(NotebookWorkingCopyTypeIdentifier._prefix.length);
		}
		return undefined;
	}