code: public static <I, O> StateLocalInputMealyMachine<Integer, I, ?, OutputAndLocalInputs<I, O>> partialToObservableOutput(
              StateLocalInputMealyMachine<Integer, I, ?, O> reference) {
          return partialToObservableOutput(reference, reference.size());
      }
docs: Convenience method for {@link #partialToObservableOutput(StateLocalInputMealyMachine, Object)}, where the size of
  the given reference is used as the new sink state.
  
  @param reference
  the (partial) mealy to transform
  @param <I>
  input symbol type
  @param <O>
  output symbol type
  
  @return see {@link #partialToObservableOutput(StateLocalInputMealyMachine, Object)}.