docs: public SyntacticCategory assignAllFeatures(String value) {
      Set<Integer> featureVars = Sets.newHashSet();
      getAllFeatureVariables(featureVars);
  
      Map<Integer, String> valueMap = Maps.newHashMap();
      for (Integer var : featureVars) {
        valueMap.put(var, value);
      }
      return assignFeatures(valueMap, Collections.<Integer, Integer>emptyMap());
    }