How to use the @jupyterlab/cells.CellDragUtils.findCell function in @jupyterlab/cells

let target = event.target as HTMLElement;
    let cellFilter = (node: HTMLElement) =>
      node.classList.contains(CONSOLE_CELL_CLASS);
    let cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);

    if (cellIndex === -1) {
      // `event.target` sometimes gives an orphaned node in
      // Firefox 57, which can have `null` anywhere in its parent line. If we fail
      // to find a cell using `event.target`, try again using a target
      // reconstructed from the position of the click event.
      target = document.elementFromPoint(
        event.clientX,
        event.clientY
      ) as HTMLElement;
      cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);
    }

    if (cellIndex === -1) {
      return;
    }

    const cell = this._cells.get(cellIndex);

    let targetArea: CellDragUtils.ICellTargetArea = CellDragUtils.detectTargetArea(
      cell,
      event.target as HTMLElement
    );

    if (targetArea === 'prompt') {
      this._dragData = {
        pressX: event.clientX,

private _evtMouseDown(event: MouseEvent): void {
    const { button, shiftKey } = event;

    // We only handle main or secondary button actions.
    if (
      !(button === 0 || button === 2) ||
      // Shift right-click gives the browser default behavior.
      (shiftKey && button === 2)
    ) {
      return;
    }

    let target = event.target as HTMLElement;
    let cellFilter = (node: HTMLElement) =>
      node.classList.contains(CONSOLE_CELL_CLASS);
    let cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);

    if (cellIndex === -1) {
      // `event.target` sometimes gives an orphaned node in
      // Firefox 57, which can have `null` anywhere in its parent line. If we fail
      // to find a cell using `event.target`, try again using a target
      // reconstructed from the position of the click event.
      target = document.elementFromPoint(
        event.clientX,
        event.clientY
      ) as HTMLElement;
      cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);
    }

    if (cellIndex === -1) {
      return;
    }

private _evtMouseDown(event: MouseEvent): void {
    const { button, shiftKey } = event;

    // We only handle main or secondary button actions.
    if (
      !(button === 0 || button === 2) ||
      // Shift right-click gives the browser default behavior.
      (shiftKey && button === 2)
    ) {
      return;
    }

    let target = event.target as HTMLElement;
    let cellFilter = (node: HTMLElement) =>
      node.classList.contains(CONSOLE_CELL_CLASS);
    let cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);

    if (cellIndex === -1) {
      // `event.target` sometimes gives an orphaned node in
      // Firefox 57, which can have `null` anywhere in its parent line. If we fail
      // to find a cell using `event.target`, try again using a target
      // reconstructed from the position of the click event.
      target = document.elementFromPoint(
        event.clientX,
        event.clientY
      ) as HTMLElement;
      cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);
    }

    if (cellIndex === -1) {
      return;
    }

let target = event.target as HTMLElement;
    let cellFilter = (node: HTMLElement) =>
      node.classList.contains(CONSOLE_CELL_CLASS);
    let cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);

    if (cellIndex === -1) {
      // `event.target` sometimes gives an orphaned node in
      // Firefox 57, which can have `null` anywhere in its parent line. If we fail
      // to find a cell using `event.target`, try again using a target
      // reconstructed from the position of the click event.
      target = document.elementFromPoint(
        event.clientX,
        event.clientY
      ) as HTMLElement;
      cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);
    }

    if (cellIndex === -1) {
      return;
    }

    const cell = this._cells.get(cellIndex);

    let targetArea: CellDragUtils.ICellTargetArea = CellDragUtils.detectTargetArea(
      cell,
      event.target as HTMLElement
    );

    if (targetArea === 'prompt') {
      this._dragData = {
        pressX: event.clientX,

let target = event.target as HTMLElement;
    let cellFilter = (node: HTMLElement) =>
      node.classList.contains(CONSOLE_CELL_CLASS);
    let cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);

    if (cellIndex === -1) {
      // `event.target` sometimes gives an orphaned node in
      // Firefox 57, which can have `null` anywhere in its parent line. If we fail
      // to find a cell using `event.target`, try again using a target
      // reconstructed from the position of the click event.
      target = document.elementFromPoint(
        event.clientX,
        event.clientY
      ) as HTMLElement;
      cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);
    }

    if (cellIndex === -1) {
      return;
    }

    const cell = this._cells.get(cellIndex);

    let targetArea: CellDragUtils.ICellTargetArea = CellDragUtils.detectTargetArea(
      cell,
      event.target as HTMLElement
    );

    if (targetArea === 'prompt') {
      this._dragData = {
        pressX: event.clientX,

private _evtMouseDown(event: MouseEvent): void {
    const { button, shiftKey } = event;

    // We only handle main or secondary button actions.
    if (
      !(button === 0 || button === 2) ||
      // Shift right-click gives the browser default behavior.
      (shiftKey && button === 2)
    ) {
      return;
    }

    let target = event.target as HTMLElement;
    let cellFilter = (node: HTMLElement) =>
      node.classList.contains(CONSOLE_CELL_CLASS);
    let cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);

    if (cellIndex === -1) {
      // `event.target` sometimes gives an orphaned node in
      // Firefox 57, which can have `null` anywhere in its parent line. If we fail
      // to find a cell using `event.target`, try again using a target
      // reconstructed from the position of the click event.
      target = document.elementFromPoint(
        event.clientX,
        event.clientY
      ) as HTMLElement;
      cellIndex = CellDragUtils.findCell(target, this._cells, cellFilter);
    }

    if (cellIndex === -1) {
      return;
    }