return (obj != null) && (obj instanceof SimpleAttributeSet) && ((SimpleAttributeSet)obj).tab.equals(this.tab);
return (obj instanceof AttributeSet) && this.isEqual((AttributeSet) obj);
  public boolean equals(Object obj)  {    return (obj != null)       && (obj instanceof SimpleAttributeSet)      && ((SimpleAttributeSet)obj).tab.equals(this.tab);  }