Hello!

I am very a new Cadabra user and I am trying to expand partial derivative of a vector field A i.e. $\partial_{\mu} { A^{\mu} }$ with the following snippet of code:

```
{A^t,A^x, A^y, A^z}::Depends(\partial{#});
A := {A^{t}=A^t,A^{x}=A^x, A^{y}=A^y, A^{z}=A^z};
dA:=\partial_{\mu}{ A^{\mu} };
evaluate(dA,A);
```

which returns an error:
`RuntimeError: Dependencies on derivatives are not yet handled in the SymPy bridge`

I ideally want it to give me the componenet expansion like: $ \partial_{\mu} { A^{\mu} } = - \partial_t A^t + \partial_x A^x + \partial_y A^y + \partial_z A^z $.

Also I want it to return a 2x2 matrix when I try to evaulate $ \partial_{\mu} { A^{\nu} } $.

Thanks in advance!