Very cool. I like this parallel execution of the original version and the update with comparisons between the two. They use a ruby package developed in house

Very cool. I like this parallel execution of the original version and the update with comparisons between the two. They use a ruby package developed in house that has been made open source, Scientist. Does anyone know if there is an similar type package for python (preferably 2.7) development? It seems like an interesting area in between unit tests and A/B tests.