Parallel states with Python's transitions package?

It is possible to implement parallel states with Python's transitions. See the documentation and search for "parallel". You will need to use the HierarchicalMachine as shown

from transitions.extensions import HierarchicalGraphMachine

An example is provided there too:

states = ['A', 'B', {'name': 'C', 
          'parallel': [{'name': '1', 'children': ['a','b','c'], 'initial':'a',
          'transitions': [['go', 'a', 'b']]},
                       {'name': '2', 'children': ['x','y','z'], 'initial':'z'}],
          'transitions': [['go', '2_z', '2_x']]}]

In order to access sub-states, you can refer to them by the {parent_child} name. For instance "C_2" would be state "2" within state "C".