friendly state machines - Python 2.7

 Automaton is a friendly state machines for Python. This state machine can be
 used to automatically run a given set of transitions and states in response to
 events (either from callbacks or from generator/iterator send() values, see
 PEP 342). On each triggered event, a on_enter and on_exit callback can also be
 provided which will be called to perform some type of action on leaving a
 prior state and before entering a new state.
 .
 This package contains the Python 2.7 module.