How to use the @lumino/domutils.Platform.accelKey function in @lumino/domutils

protected onArrowLeft(grid: DataGrid, event: KeyboardEvent): void {
    // Stop the event propagation.
    event.preventDefault();
    event.stopPropagation();

    // Fetch the selection model.
    let model = grid.selectionModel;

    // Fetch the modifier flags.
    let shift = event.shiftKey;
    let accel = Platform.accelKey(event);

    // Handle no model with the accel modifier.
    if (!model && accel) {
      grid.scrollTo(0, grid.scrollY);
      return;
    }

    // Handle no model and no modifier. (ignore shift)
    if (!model) {
      grid.scrollByStep('left');
      return;
    }

    // Fetch the selection mode.
    let mode = model.selectionMode;

protected onKeyC(grid: DataGrid, event: KeyboardEvent): void {
    // Bail early if the modifiers aren't correct for copy.
    if (event.shiftKey || !Platform.accelKey(event)) {
      return;
    }

    // Stop the event propagation.
    event.preventDefault();
    event.stopPropagation();

    // Copy the current selection to the clipboard.
    grid.copyToClipboard();
  }

protected onArrowDown(grid: DataGrid, event: KeyboardEvent): void {
    // Stop the event propagation.
    event.preventDefault();
    event.stopPropagation();

    // Fetch the selection model.
    let model = grid.selectionModel;

    // Fetch the modifier flags.
    let shift = event.shiftKey;
    let accel = Platform.accelKey(event);

    // Handle no model with the accel modifier.
    if (!model && accel) {
      grid.scrollTo(grid.scrollX, grid.maxScrollY);
      return;
    }

    // Handle no model and no modifier. (ignore shift)
    if (!model) {
      grid.scrollByStep('down');
      return;
    }

    // Fetch the selection mode.
    let mode = model.selectionMode;

protected onArrowUp(grid: DataGrid, event: KeyboardEvent): void {
    // Stop the event propagation.
    event.preventDefault();
    event.stopPropagation();

    // Fetch the selection model.
    let model = grid.selectionModel;

    // Fetch the modifier flags.
    let shift = event.shiftKey;
    let accel = Platform.accelKey(event);

    // Handle no model with the accel modifier.
    if (!model && accel) {
      grid.scrollTo(grid.scrollX, 0);
      return;
    }

    // Handle no model and no modifier. (ignore shift)
    if (!model) {
      grid.scrollByStep('up');
      return;
    }

    // Fetch the selection mode.
    let mode = model.selectionMode;

protected onPageDown(grid: DataGrid, event: KeyboardEvent): void {
    // Ignore the event if the accel key is pressed.
    if (Platform.accelKey(event)) {
      return;
    }

    // Stop the event propagation.
    event.preventDefault();
    event.stopPropagation();

    // Fetch the selection model.
    let model = grid.selectionModel;

    // Scroll by page if there is no selection model.
    if (!model || model.selectionMode === 'column') {
      grid.scrollByPage('down');
      return;
    }

protected onPageUp(grid: DataGrid, event: KeyboardEvent): void {
    // Ignore the event if the accel key is pressed.
    if (Platform.accelKey(event)) {
      return;
    }

    // Stop the event propagation.
    event.preventDefault();
    event.stopPropagation();

    // Fetch the selection model.
    let model = grid.selectionModel;

    // Scroll by page if there is no selection model.
    if (!model || model.selectionMode === 'column') {
      grid.scrollByPage('up');
      return;
    }

let { clientX, clientY } = event;

    // Hit test the grid.
    let hit = grid.hitTest(clientX, clientY);

    // Unpack the hit test.
    let { region, row, column } = hit;

    // Bail if the hit test is on an uninteresting region.
    if (region === 'void') {
      return;
    }

    // Fetch the modifier flags.
    let shift = event.shiftKey;
    let accel = Platform.accelKey(event);

    // If the hit test is the body region, the only option is select.
    if (region === 'body') {
      // Fetch the selection model.
      let model = grid.selectionModel;

      // Bail early if there is no selection model.
      if (!model) {
        return;
      }

      // Override the document cursor.
      let override = Drag.overrideCursor('default');

      // Set up the press data.
      this._pressData = {