This breaks when running with python -OO (optimized) which
removes the documentation but is crucial. Instead and thanks
to fce5cfea, we can now rely on the type hints instead.
This is another attempt at reducing CPU usage similar to:
1b6b4a57d9
In addition it simplifies some of the code and opens up new
ideas for the state cache as well.
Plenty of unnecessary exceptions were being raised and caught when
the input parameters were already correct. Furthermore, since
8abc7ade22, the in-disk cache was no
longer being used (so using usernames always reached out to memory).
