Question: I am trying to write an excel `XLOOKUP` query.

Where I have 2 table -

**Table 1**

```
Email           Found/Not Found
user1@ss.se
user2@ss.se    
user3@ss.se
user4@ss.se

```

**Table 2**

```
Email
user2@ss.se    
user3@ss.se

```

In `table 1` I want to find if any of the `emails` can be found in `table 2`. If the `emails` is found the result should be `found` else `not found`

**Expected result**

```
Email          Found/Not Found
user1@ss.se   Not Found
user2@ss.se    Found
user3@ss.se   Found
user4@ss.se   Not Found

```

I have tried this query but it is giving me an error message

```
=XLOOKUP(A2;table2!A2:A5;"Found";"";0)

```

Answer: 
See [Mutating and Returning State](https://redux-toolkit.js.org/usage/immer-reducers#mutating-and-returning-state) doc

> 
> Immer expects that you will either mutate the existing state, or construct a new state value yourself and return it, but not both in the same function! For example, both of these are valid reducers with Immer:
> 
> 
> 

```js
const todosSlice = createSlice({
  name: 'todos',
  initialState: [],
  reducers: {
    todoAdded(state, action) {
      // "Mutate" the existing state, no return value needed
      state.push(action.payload)
    },
    todoDeleted(state, action.payload) {
      // Construct a new result array immutably and return it
      return state.filter(todo => todo.id !== action.payload)
    }
  }
})

```
State becomes "mutable" when you are defining reducers inside RTK `createSlice`. You can therefore use `push` to update your state without returning it.