Change `id` in all classes to string and make it optional arg

[Nikronic]

Currently, id is a mandatory int value to be filled. Actually, the value itself represents no meaning, so I think it would be better to change it to string then name it through different functions at the time of initializing to make it easier to trace bugs or process.

suggested default value: unnamed other states names: `{current_scope_func_name_[within if\within else, etc]}