I need to assure that capacity is enough, i mean, for something like an array just doubling size is good because you are storing things that are the same size but for something like an arena you could actually store anything so we need to make sure the growth factor stays cool while an overflow doesn't occur, that's why the change with arena_calculate_capacity and also changing signatrues to use results, A LOT of boilerplate but i guess is fine for me.