code: public static <A,S> Transition<A,S> create(S fromState, A action, S toState){
          return new Transition<A, S>(fromState, action, toState);
      }
docs: Instantiates a transition specifying an action, the origin and
  destination states.
  
  @param fromState state origin of the transition
  @param action action associated to this transition
  @param toState state destination of the transition
  @param <A> type of the actions
  @param <S> type of the state
  @return instance of a transition with an origin, destination and action