code: def notGroup (states, *stateIndexPairs):
      
      start, dead = group(states, *stateIndexPairs)
      finish = len(states)
      states.append([])
      states[start].append((DEFAULT, finish))
      return start, finish
docs: Like group, but will add a DEFAULT transition to a new end state,
      causing anything in the group to not match by going to a dead state.
      XXX I think this is right...