Release 0.8.0 is a major release and introduces asyncio support for Python 3.7+, parallel state support and some bugfixes Feature: HierarchicalMachine has been rewritten to support parallel states. Please have a look at the ReadMe.md to check what has changed. The previous version can be found in transitions.extensions.nesting_legacy for now Feature: Introduced AsyncMachine (see discussion #259); note that async HSMs are not yet supported Feature #390: String callbacks can now point to properties and attributes (thanks @jsenecal) Bugfix: Auto transitions are added multiple times when add_states is called more than once Bugfix: Convert state._name from Enum into strings in MarkupMachine when necessary Bugfix #392: Allow Machine.add_ordered_transitions to be called without the initial state (thanks @mkaranki and @facundofc) GraphMachine now attempts to fall back to graphviz when importing pygraphviz fails Not implemented/tested so far (contributions are welcome!): Proper Graphviz support of parallel states AsyncHierachicalMachine