Small things that make the life of a developer easier and improve
numerical precision in corner cases.
I just went over some statsmodels code that was written maybe 5 years
ago with clumsy or missing 0*log(0) = 0 handling.
scipy.special has been and is getting nice little (*) functions that
handle some corner cases automatically and numerically in a more
stable way. scipy.stats is one of the beneficiaries.
Thanks to several maintainer/developers and contributors.
(*) little compared to the heavy stuff in scipy.special, but also useful
(apropos heavy: 5 papers mention that there is no closed form solution
for the pmf of a discrete distribution but we can calculate it using a
recursion. The 6th article mentions it can be calculated with the
modified Bessel function of the second kind.
Why didn't they say so right away. I'd rather use scipy.special than
figuring out how to do a numerically stable recursion.)