@Override
    public void unknown(UnknownType type) {
      final TypeModel nested = type.type;
      if (nested != null) {
        if (type.bitwiseOrUnionAllowed) {
          nested.accept(this);
          add(HtmlChunk.raw(" | " + PyNames.UNKNOWN_TYPE));
        }
        else {
          add(HtmlChunk.raw("Union[")); // NON-NLS
          nested.accept(this);
          add(HtmlChunk.raw(", " + PyNames.UNKNOWN_TYPE + "]"));
        }
      }
    }
@Override
    public void unknown(UnknownType type)