MainViewModel.kt

class MainFragment: Fragment(){
    ...
    ...
    ...
    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel._onActivityCreated.call()
    }
    ...
    ...
    ...
}

class MainViewModel(private val getTodoUsecase: GetTodoUsecases) : ViewModel() {

    val _onActivityCreated = SingleLiveEvent<Any>()

    private val responseResult: LiveData<ResponseResult<Todo>> = Transformations.map(_onActivityCreated) {
        getTodoUsecase()
    }

    val todoResult: LiveData<Todo> = Transformations.switchMap(responseResult) {
        it.data
    }

    val errorResult: LiveData<ResponseError> = Transformations.switchMap(responseResult) {
        it.error
    }
}