code: func (as AnnotatedSentence) Lemmas() []string {
  	lemmas := make([]string, len(as))
  	for i, a := range as {
  		lemmas[i] = a.Lemma
  	}
  	return lemmas
  }
docs: // Lemmas returns the lemmas as as slice of string. The return value has exactly the same length as the sentence.