Let there is an object which has values as arrays. For example,

```
    const obj = {
      'abc': ['xyz','tuv'],
      'def': ['qrs']
    }

```

How can we get the key of 'tuv' from the object?

This is different from this question, where the value was not an array. 
 [How to get a key in a JavaScript object by its value?](https://stackoverflow.com/questions/9907419/how-to-get-a-key-in-a-javascript-object-by-its-value)