code: def addTransition(self, state, input, output, nextState):
          
          return self.addTransitions(state, {input: (output, nextState)})
docs: Create a new L{TransitionTable} with all the same transitions as this
          L{TransitionTable} plus a new transition.
  
          @param state: The state for which the new transition is defined.
          @param input: The input that triggers the new transition.
          @param output: The output produced by the new transition.
          @param nextState: The state that will follow the new transition.
  
          @return: The newly created L{TransitionTable}.