I need to learn the right way to do pattern matching on Pair types:

```
let pairToBeFiltered = Ok ([(1,[]);(2,[3;4]);(5,[6;7;8]);(9,[]);(10,[])])

let filterEmpty (pair: int * int list) =
    match pair with
    | (x,y) when y <> [] -> (x,y) //This gives error because of incomplete pattern matching!

let filtering = List.map(filterEmpty) pairToBeFiltered

```

Desired output:

```
Ok([(2,[3;4]);(5,[6;7;8])])

```