Extract dimensionless quantities?

I've got some code that performs a division that removes all dimensions

```haskell
a :: Mass SI n
b :: Mass SI n
c :: Qu '[] SI n
c = a |/| b
```

I need to extract this `n` for further processing by another library. Would it make sense to add

```haskell
extract :: Qu '[] l n -> n
extract = coerce
```
?