we mostly use pre-calculated indexes, ie integers
but registers are allowed (in arm/risc), so we try to check the registers type at least is right.
The return is really a machine word, but we call it Object (yes, more work that way)
Was getting confused myself, where it was instruction or instructions, when if the base class was inside or out of dir.
Now dirs are plural, and base class is inside.
rubydesign