The Uniform RV in PyMC3 has lower and upper bounds that make a closed interval. What’s the right way to do open intervals (e.g., Uniform > 0)? Do we just make it `Uniform(0 + ε)`

? So is this right?

```
pm.Uniform("U", np.finfo(float).eps, upper)
```

(for some value of `upper`

)