Rugby hierarchical model on both team and field

A variant of the 'rugby' ArviZ example dataset. Like the 'rugby' dataset, it contains the result of fitting a Bayesian model using PyMC to results of the Six Nations Championship.
The Six Nations Championship is a yearly rugby competition between Italy, Ireland, Scotland, England, France and Wales. Fifteen games are played each year, representing all combinations of the six teams. This example uses and includes results from 2014 - 2017, comprising 60 total games. It models latent parameters for each team's attack and defense, with each team having different values depending on them being home or away team.
See https://github.com/arviz-devs/arviz_example_data/blob/main/code/rugby_field/rugby_field.ipynb for the whole model specification."