public function vn($vn = null)
    {
        if ($vn !== null) {
            $this->vn = strtoupper($this->escape($vn));
            return $this;
        }
        return $this->vn;
    }
public function vn($vn = null)
    {
        if ($vn !== null) {
            $this->vn = strtoupper($this->escape($vn));
            return $this;
        }
        return $this->vn;
    }
public function vn ( $ vn = null ) { if ( $ vn !== null ) { $ this -> vn = strtoupper ( $ this -> escape ( $ vn ) ) ; return $ this ; } return $ this -> vn ; }
Gets or sets the verification number
@param null $vn
@return $this|null|string
Gets or sets the verification number