/**
  * Run a cell.
  */
 function runCell(parent: Notebook, child: Cell, session?: IClientSession): Promise<boolean> {
   switch (child.model.type) {
   case 'markdown':
     (child as MarkdownCell).rendered = true;
     child.inputHidden = false;
     break;
   case 'code':
     if (session) {
       return CodeCell.execute(child as CodeCell, session).then(reply => {
         if (child.isDisposed) {
           return false;
         }
         if (reply && reply.content.status === 'ok') {
           let content = reply.content as KernelMessage.IExecuteOkReply;
           if (content.payload && content.payload.length) {
             handlePayload(content, parent, child);
           }
         }
         return reply ? reply.content.status === 'ok' : true;
       }).catch(e => {
         if (e.message !== 'Canceled') {
           throw e;
         }
         return false;
       });
     }
     (child.model as ICodeCellModel).executionCount = null;
     break;
   default:
     break;
   }
   return Promise.resolve(true);
 }

 execute: () => CodeCell.execute(cellWidget, session)

function main(): void {
  const manager = new SessionManager();
  const session = new ClientSession({ manager, name: 'Example' });
  const mimeService = new CodeMirrorMimeTypeService();

  // Initialize the command registry with the bindings.
  const commands = new CommandRegistry();
  const useCapture = true;

  // Setup the keydown listener for the document.
  document.addEventListener('keydown', event => {
    commands.processKeydownEvent(event);
  }, useCapture);

  // Create the cell widget with a default rendermime instance.
  const rendermime = new RenderMimeRegistry({ initialFactories });

  const cellWidget = new CodeCell({
    rendermime,
    model: new CodeCellModel({})
  });

  // Handle the mimeType for the current kernel.
  session.kernelChanged.connect(() => {
    session.kernel.ready.then(() => {
      const lang = session.kernel.info.language_info;
      const mimeType = mimeService.getMimeTypeByLanguage(lang);
      cellWidget.model.mimeType = mimeType;
    });
  });

  // Start the default kernel.
  session.kernelPreference = { autoStartDefault: true };
  session.initialize();

  // Set up a completer.
  const editor = cellWidget.editor;
  const model = new CompleterModel();
  const completer = new Completer({ editor, model });
  const connector = new KernelConnector({ session });
  const handler = new CompletionHandler({ completer, connector });

  // Set the handler's editor.
  handler.editor = editor;

  // Hide the widget when it first loads.
  completer.hide();

  // Create a toolbar for the cell.
  const toolbar = new Toolbar();
  toolbar.addItem('spacer', Toolbar.createSpacerItem());
  toolbar.addItem('interrupt', Toolbar.createInterruptButton(session));
  toolbar.addItem('restart', Toolbar.createRestartButton(session));
  toolbar.addItem('name', Toolbar.createKernelNameItem(session));
  toolbar.addItem('status', Toolbar.createKernelStatusItem(session));

  // Lay out the widgets.
  const panel = new BoxPanel();
  panel.id = 'main';
  panel.direction = 'top-to-bottom';
  panel.spacing = 0;
  panel.addWidget(completer);
  panel.addWidget(toolbar);
  panel.addWidget(cellWidget);
  BoxPanel.setStretch(toolbar, 0);
  BoxPanel.setStretch(cellWidget, 1);

  // Attach the panel to the DOM.
  Widget.attach(panel, document.body);

  // Handle widget state.
  window.addEventListener('resize', () => { panel.update(); });
  cellWidget.activate();

  // Add the commands.
  commands.addCommand('invoke:completer', {
    execute: () => { handler.invoke(); }
  });
  commands.addCommand('run:cell', {
    execute: () => CodeCell.execute(cellWidget, session)
  });

  commands.addKeyBinding({
    selector: '.jp-InputArea-editor.jp-mod-completer-enabled',
    keys: ['Tab'],
    command: 'invoke:completer'
  });
  commands.addKeyBinding({
    selector: '.jp-InputArea-editor',
    keys: ['Shift Enter'],
    command: 'run:cell'
  });
}

 matchedCells.forEach((cell) => {
   cell instanceof CodeCell && CodeCell.execute(cell, session);
 });