My late christmas present for you: context-aware assertion error messages

[Kagamin]

On Tuesday, 15 January 2019 at 10:23:32 UTC, Seb wrote:
> My main motivation was to be able to see the actual values 
> (instead of just an AssertError), so I would be more than happy 
> to change the format of the message.

I remember Adam wanted the asserted expression to be printed as 
is to more reliably locate the failed assert as it can move when 
the code changes. Did you consider it?
So the message can be "assertion a == b failed: a=1,b=2".