adt Twine{
	Null
	CStr(cstr:ptr u8)
	StringView(view:string_view)
	Twine(lhs rhs:ref Twine)

	method length(self:ref Twine):uword{
		switch(self){
		case Null: return 0;
		case CStr(cstr): return strlen(cstr);
		case StringView(view): return view.size();
		case Twine(lhs, rhs): return lhs.length() + rhs.length();
		}
	}

}