code: public SequenceInput<Annotation> asSequence(@NonNull Function<? super Annotation, String> labelFunction) {
        SequenceInput<Annotation> si = new SequenceInput<>();
        for (Annotation token : tokens()) {
           si.add(token, labelFunction.apply(token));
        }
        return si;
     }
docs: Creates a labeled {@link SequenceInput} of tokens from this HString applying the given label function to each
  token to determine its label, i.e. class..
  
  @param labelFunction the label function to determine the label (or class) of the data point (e.g. part-of-speech,
  sentiment, etc.)
  @return the sequence input