Is there a more succinct way to do this?

```
ka = KeyedArray( ones(2,2), I=[:a,:b], J=[:x,:y] )
@tullio x[i,j] := ( ka[i,j], axiskeys(ka)[1][i], axiskeys(ka)[2][j])
```

Something like

```
@tullio x[i,j] := ( ka(i,j), i, j )
```

That is, can the dummy variables `i,j`

refer to the named keys rather that numbered indices.