Say I have

```
x = [1 2]
y = [10, 20, 30]
f(a,b) = a+b+0.5
```

I want an iterator that goes through the elements of `f.(x,y)`

(11.5, 21.5, 31.5, …) without allocating the output array. Bonus points for an iterator that can also give the indices of `x`

, `y`

, and their nonexistent broadcasted output per iteration: (1,1,1), (1,2,2), (1,3,3), … That last bit might be a bit trickier for arrays that don’t allow linear indexing.