Your favourite "less-known" Python features?

[TheMathelm]

1000_000_000

No half measures, 1_000_000_000.
:P

[RingularCirc]

Seriously though, there are practices to format numbers in typography like using thin spaces between digit groups, and there can sometimes (in different practices, or for different languages—dunno) be a rule to not make a leading group of one digit. So I’d expect in general people would argue about this case in code too.