src/vs/workbench/contrib/notebook/browser/notebookExecutionStateServiceImpl.ts/NotebookExecutionStateService/getCellExecution
class NotebookExecutionStateService:	getCellExecution(cellUri: URI): INotebookCellExecution | undefined {
		const parsed = CellUri.parse(cellUri);
		if (!parsed) {
			throw new Error(`Not a cell URI: ${cellUri}`);
		}

		const exeMap = this._executions.get(parsed.notebook);
		if (exeMap) {
			return exeMap.get(parsed.handle);
		}

		return undefined;
	}