I'm creating a React + Redux app, but I'm unsure on how to go about this reducer.

Following the example on [real-word](https://github.com/reactjs/redux/blob/master/examples/real-world/) I'm using the following code to store my entities.

```
// Updates an entity cache in response to any action with response.entities.

const entities = (state = initialState, action) => {
  if (action.response && action.response.entities) {
    return merge({}, state, action.response.entities)
  }

  return state
}

```

The question is: How can I handle an update on a nested entity? Everything is already normalized, so it would be a matter of getting the keys and updating them, but I can't figure out how.

I could use the example from the [docs](http://redux.js.org/docs/recipes/reducers/UpdatingNormalizedData.html), but it only shows how to solve a simple case, where there are only 2 entities so I can have one reducer for each. I have 8 (and possibly more) entities and it would be a lot of work to create one reducer for each, with every action for fetching and receiving, but maybe that's the approach I should take?