vm/ops.go
func txMarkRaw(st *State) {
	if reflect.ValueOf(st.sa).Type() != rawStringType {
		st.sa = rawString(interfaceToString(st.sa))
	}
	st.Advance()
}
func txMarkRaw(st *State) {
	if reflect.ValueOf(st.sa).Type() != rawStringType {
		st.sa = rawString(interfaceToString(st.sa))
	}
	st.Advance()
}
// Wraps the contents of register sa with a "raw string" mark
// Note that this effectively stringifies the contents of register sa