BETSE 0.8.3 (Kindly Kaufmann) released. Significant changes include: * Dill >= 0.2.8 fundamentally broke backward compatibility by renaming the public "dill.dill" submodule to "dill._dill". This stable release restores compatibility with dill >= 0.2.3, including dill >= 0.2.8. * Mapping API marginally optimized. The betse.util.type.mapping.mappings.is_keys() function has been renamed for generality to is_key() and has now been optimized for the common edge case of testing key containment for a single key.