public function unsetWorksheetCells()
    {
        if ($this->currentCell !== null) {
            $this->currentCell->detach();
            $this->currentCell = null;
            $this->currentCoordinate = null;
        }

        // Flush the cache
        $this->__destruct();

        $this->index = [];

        // detach ourself from the worksheet, so that it can then delete this object successfully
        $this->parent = null;
    }