The Polya-Gamma Distribution samplers were extracted from BayesLogit R package
with the following author and copyright information:

Copyright: 2012-2019 Nicholas Polson, James Scott, Jesse Windle

The pg package provides a refactorization of the algorithms to be self-contained
in a header-only library with additional C++ accessors. The refactorization
was done by James Joseph Balamuta.