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## Breaking changes

 - Minor interface changes to [MCMC utility](http://num.pyro.ai/en/latest/utilities.html#module-numpyro.infer.util) functions. All experimental interfaces are marked as such in the documentation.

## New Features

 - A [numpyro.factor](http://num.pyro.ai/en/latest/primitives.html#numpyro.primitives.factor) primitive that adds an arbitrary log probability factor to a probabilistic model.

## Enhancements and Bug Fixes

 - Addressed a bug where multiple invocations of `MCMC.run` would wrongly use the previously cached arguments.
 - `MCMC` reuses compiled model code whenever possible. e.g. when re-running with different but same sized model arguments.
 - Ability to reuse the same warmup state for subsequent MCMC runs using [MCMC.warmup](http://num.pyro.ai/en/latest/mcmc.html#numpyro.infer.mcmc.MCMC.warmup).