@Override public String debugPrint(){
  DebugPrintVisitor dpv=new DebugPrintVisitor(new StringBuilder(1000));
  visitAll(dpv);
  return dpv.toString();
}

@ Override public String debugPrint ( ) { DebugPrintVisitor dpv = new DebugPrintVisitor ( new StringBuilder ( 1000 ) ) ; visitAll ( dpv ) ; return dpv . toString ( ) ; }
a debug - printer that includes comments ( at the end ) .
