public function labelType() : ?int
    {
        if (!isset($this->labels[0])) {
            return null;
        }

        return DataType::determine($this->labels[0]);
    }
public function labelType() : ?int
    {
        if (!isset($this->labels[0])) {
            return null;
        }

        return DataType::determine($this->labels[0]);
    }
public function labelType ( ) : ? int { if ( ! isset ( $ this -> labels [ 0 ] ) ) { return null ; } return DataType :: determine ( $ this -> labels [ 0 ] ) ; }
Return the integer encoded data type of the label or null if empty.

@return int|null
Return the integer encoded data type of the label or null if empty .