It's the domain knowledge that's difficult. Like the example up thread about the lack of generalised additive models. The version in R was written originally by

It's the domain knowledge that's difficult. Like the example up thread about the lack of generalised additive models. The version in R was written originally by the developers of the method. There's no Python version because no one with sufficient expertise has ported it. Don't get me wrong, I know mostly write Python because it's a better general purpose language but there are big big tradeoffs.