lib/BN.php
public function iadd(BN $num) {
        $this->bi = $this->bi->add($num->bi);
        return $this;
    }
public function iadd(BN $num) {
        $this->bi = $this->bi->add($num->bi);
        return $this;
    }
public function iadd ( BN $ num ) { $ this -> bi = $ this -> bi -> add ( $ num -> bi ) ; return $ this ; }
Add `num` to `this` in-place
Add num to this in - place