This allows you to use back-access syntax to access items in an array or characters in a string.

Algorithmically speaking, it just adds the negative integer in `arr[-1]` to the length of the array/string and tries to search for that property inside the object.

### Examples

```js
const arr = backAccess(['first', 'second', 'last'])
arr[-1] // => "last"
arr[-2] // => "second"
arr[-3] // => "first"

const str = backAccess('Hello world!')
str[-1] // => "!"
str[-2] // => "d"
str[-3] // => "l"

```

### Conclusion

Proxies are awesome! But maybe a bit useless in practical terms xD