Transformer pi-model documentation

[Robin Henry]

Hello,

Correct me if I am wrong, but I believe the equations presented in the doc that relate currents and voltages in the pi-model of transformers (https://pypsa.readthedocs.io/en/latest/power_flow.html) have been mismatched, i.e., the equation presented for tap_side=0 actually matches the case for tap_side=1 (and vice-versa). 

It would seem that the error is only present in the documentation, though, and that the implementation is correct. Could someone confirm this?

Thanks a lot,

Best,

Robin