docs: public SyntacticCategory stripFeatures(Set<String> atomicCategoriesToStrip) {
      if (isAtomic()) {
        if (atomicCategoriesToStrip.contains(value) && !featureValue.equals(DEFAULT_FEATURE_VALUE)) {
          return SyntacticCategory.createAtomic(value, DEFAULT_FEATURE_VALUE, -1);
        } else {
          return this;
        }
      } else {
        return SyntacticCategory.createFunctional(direction, returnType.stripFeatures(atomicCategoriesToStrip), 
            argumentType.stripFeatures(atomicCategoriesToStrip), featureValue, featureVariable);
      }
    }