public function label(int $index)
    {
        if (!isset($this->labels[$index])) {
            throw new InvalidArgumentException("Row at offset $index"
                . ' does not exist.');
        }

        return $this->labels[$index];
    }
public function label(int $index)
    {
        if (!isset($this->labels[$index])) {
            throw new InvalidArgumentException("Row at offset $index"
                . ' does not exist.');
        }

        return $this->labels[$index];
    }
public function label ( int $ index ) { if ( ! isset ( $ this -> labels [ $ index ] ) ) { throw new InvalidArgumentException ( "Row at offset $index" . ' does not exist.' ) ; } return $ this -> labels [ $ index ] ; }
Return a label given by row index.

@param int $index
@throws \InvalidArgumentException
@return int|float|string
Return a label given by row index .