There's probably a simple command to do this but I can't seem to find it. How do I simplify products of scalar functions whose partial derivatives are non-vanishing?

```
{a, b, c, d}::Indices(space1, position=independent).
\partial{#}::PartialDerivative.
f::Depends(\partial{#}).
ex:= f * f**2 * f**(-5);
```

How do I simplify this expression? Without the dependence on the partial derivatives the following works

`simplify(ex);`