-*- outline -*-
 
* Things to do:
** Machine#state=(String|Array).
** Add :elapsed_time to history Hash - has performance implication.
** Support StateMachine#freeze to avoid accidental changes to a running StateMachine.
** Support UML Pseudostates.
** Support UML Regions.
** Support UML History, Deep History Pseudostate semantics.
** Support UML Transition#kind.
** Remove State#state_type and support UML FinalState.
 
* Jeremy's Comments:
** Having to call start! explicitly is troublesome.
** Setting Machine#context more than once could cause confusion.
** Need a way to do Statemachine#freeze, which will throw errors if new states/transitions are added.
** When you enter into a substate, lazyly create a Submachine.
  "This will not be implemented as it is counter to UML semantics"
** Need to have a way to disable Machine#context= and Machine#state= to prevent foolishness.
** There is an implied nil "start!" transition in the Machine#history,
not sure what to do about this.
 
* Dean's Comments:
** Machine#run! is a terrible name since it may return before Machine#at_end? is true.