Another thing that bugs me: if you have a function argument then it is copied by value, right? But it is hard to tell if the whole value is copied or not.

- structures argument: the whole structure is copied (unless you passed a pointer to the struct)

- interface? depends if the implementation is structure or pointer.

- maps: it copies just a small internal struct that is pointing to the implementation of the map.

- arrays: depends if it is a slice then copy cost is small (again, similar to maps), however an array is fully copied.

... complicated.