1. Formatting -- black style! 2. After profiling, implemented a better workaround for the tfd.Categorical bug. Replaced with an inherited Categorical2 class, with overloaded log_prob function. 3. Fixed a bug in EventTimeProposal where tfd.FiniteDiscrete was being used on a non-strictly-increasing outcomes vector. 4. Increased number of meta-populations to 149 to mirror UK UTLA regions.