(whistling)

It's wat I did in JavaScript too. Rather dissappointing that the tests do not look for this efficiency.

Maybe you should add that to the description, phantamanta44?

Resolved!

you can't use any fields or parameters that aren't of type NaturalNumber (except in Object#equals(Object)) and you can't define any classes other than NaturalNumber.

To be more precise, you cannot use either enums or interfaces or other classes.

That's the way I did it! Resolved this kata before viewing your post here. Glad that we think alike. :D

That sounds like a very smart solution. CodeWars isn't showing your solution, can you link to it or post it here?

I modified the description slightly. Hopefully that clears things up.

-	* `[tab]`: Pop `a` and then push the value at heap address `a`.
+	* `[tab]`: Pop `a` and then push the value at heap address `a` onto the stack.