implement custom subscription on redux store

example.js

const initialTodosState = [];
const initialCounterState = 0;

function todos(state = initialTodosState, action) {
  return state;
}

function counter(state = initialCounterState, action) {
  return state;
}

const reducer = combineReducers({ todos, counter }});
const store = createStore(reducer);

// right now my store structure looks like:
// store.getState() => 
// {
//   todos: [...],
//   counter: 0
// }

// how could I subscribe on update only `todos` subtree or `counter`?

the default method store.subscribe(handler) allows to sibscribe only on root (my handler will be invoked after every changes, counter and todos)