I cannot seem to figure out how to run a `LinReg`

Onlinestat on my JuliaDB table. Especially, how to tell the `reduce`

function what the left-hand-side and right-hand-side variables are. The following runs a regression of `y`

on `x`

and `z`

is ignored:

```
t = table(@NT(x = randn(1000), y = randn(1000), z = rand(1000)))
reduce(LinReg(), t, select = (:x, :y, :z))
```