code: public TTTTransition<I, D> getInternalTransition(TTTState<I, D> state, I input) {
          int inputIdx = alphabet.getSymbolIndex(input);
          return getInternalTransition(state, inputIdx);
      }
docs: Retrieves the <i>internal</i> transition (i.e., the {@link TTTTransition} object) for a given state and input.
  This method is required since the {@link DFA} interface requires the return value of {@link
  #getTransition(TTTState, Object)} to refer to the successor state directly.
  
  @param state
  the source state
  @param input
  the input symbol triggering the transition
  
  @return the transition object