Variational fit (ADVI) - initialisation

I started looking into the implementation of ADVI in pymc/variational/inference.py, but I am really having a hard time introspecting the code in order to understand how to correctly set start and start_sigma - in fact I don’t see how those extra arguments are forwarded to the actual ADVI fit implementation.

@ricardoV94 @schmaus would you be able to give me some pointers here?