    function add_presale_arbits_sold(address db, uint256 _v) internal {
        uint256 c = database(db).get_presale_arbits_sold() + _v;      
        assert(c >= database(db).get_presale_arbits_sold());  
        database(db).set_presale_arbits_sold(
            (database(db).get_presale_arbits_sold() + _v)
        );
        emit e_add_presale_arbits_sold(_v);
    }