public function hasCell($columnKey, $rowKey) : bool
    {
        $this->validateColumnKey(__METHOD__, $columnKey);
        $this->validateRowKey(__METHOD__, $rowKey);

        $this->loadColumns();
        $this->loadRows();

        $columnHash = ValueHasher::hash($columnKey);
        if (!isset($this->columns[$columnHash])) {
            return false;
        }

        $rowHash = ValueHasher::hash($rowKey);
        if (!isset($this->rows[$rowHash])) {
            return false;
        }

        return true;
    }