from largeman import StateMachine

sm = StateMachine()
sm.add_state('on')
sm.add_state('off')

sm.add_transition('on', 'turn_off', 'off')
sm.add_transition('off', 'turn_on', 'on')

s = sm('off')

s.turn_on()
assert s.current == 'on'

s.turn_off()
assert s.current == 'off'