protected @Nullable ZenCodingNode parseMoreOperation(@Nullable ZenCodingNode leftPart) {
    advance();
    ZenCodingNode rightPart = parseAddOrMore();
    if (rightPart == null) {
      return leftPart;
    }
    return new MoreOperationNode(notNullNode(leftPart), rightPart);
  }
protected @Nullable ZenCodingNode parseMoreOperation(@Nullable ZenCodingNode leftPart)