@Override
  protected Object clone() throws CloneNotSupportedException {
    SyntaxTable cl = (SyntaxTable)super.clone();
    cl.myKeywords1 = new HashSet<>(myKeywords1);
    cl.myKeywords2 = new HashSet<>(myKeywords2);
    cl.myKeywords3 = new HashSet<>(myKeywords3);
    cl.myKeywords4 = new HashSet<>(myKeywords4);
    cl.myKeywordParser = null;
    return cl;
  }
@Override
  protected Object clone()