Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Worksheet/ColumnIterator.php
public function prev()
    {
        if ($this->currentColumnIndex <= $this->startColumnIndex) {
            throw new PhpSpreadsheetException('Column is already at the beginning of range (' . Coordinate::stringFromColumnIndex($this->endColumnIndex) . ' - ' . Coordinate::stringFromColumnIndex($this->endColumnIndex) . ')');
        }
        --$this->currentColumnIndex;
    }
public function prev()
    {
        if ($this->currentColumnIndex <= $this->startColumnIndex) {
            throw new PhpSpreadsheetException('Column is already at the beginning of range (' . Coordinate::stringFromColumnIndex($this->endColumnIndex) . ' - ' . Coordinate::stringFromColumnIndex($this->endColumnIndex) . ')');
        }
        --$this->currentColumnIndex;
    }
Set the iterator to its previous value.

@throws PhpSpreadsheetException