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

// 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,
        pressY: event.clientY,
        index: cellIndex
      };

      this._focusedCell = cell;

      document.addEventListener('mouseup', this, true);
      document.addEventListener('mousemove', this, true);
      event.preventDefault();

// 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,
        pressY: event.clientY,
        index: cellIndex
      };

      this._focusedCell = cell;

      document.addEventListener('mouseup', this, true);
      document.addEventListener('mousemove', this, true);
      event.preventDefault();

// 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,
        pressY: event.clientY,
        index: cellIndex
      };

      this._focusedCell = cell;

      document.addEventListener('mouseup', this, true);
      document.addEventListener('mousemove', this, true);
      event.preventDefault();