core:

import edu.neu.ccs.demeter.*;
add: class SummingVisitor extends UniversalVisitor {
  protected int total;
  public int get_total() {{ return total; }}
  public void set_total(int new_total)
    {{ total = new_total; }}
  public constructor SummingVisitor(int total) {{
    super();
    set_total(total);
  }}
  public static SummingVisitor parse(java.io.Reader in)
    throws ParseException
  {{ return new Parser(in)._SummingVisitor(); }}
  public static SummingVisitor parse(java.io.InputStream in)
    throws ParseException
  {{ return new Parser(in)._SummingVisitor(); }}
  public static SummingVisitor parse(String s) {{
    try { return parse(new java.io.StringReader(s)); }
    catch (ParseException e) {
      throw new RuntimeException(e.toString());
    }
  }}
  public constructor SummingVisitor() {{ total = 0; }}
  public void before(Quantity host) {{ System.out.println("sum " + total); 
	total = total + host.get_number().intValue(); }}
  int get_return_val() {{ return total ; }}
{{  void universal_trv0_bef(UniversalVisitor _v_) {
    super.universal_trv0_bef(_v_);
  }
}}
{{  void universal_trv0_aft(UniversalVisitor _v_) {
    super.universal_trv0_aft(_v_);
  }
}}
{{  void universal_trv0(UniversalVisitor _v_) {
    universal_trv0_bef(_v_);
    super.universal_trv0(_v_);
    universal_trv0_aft(_v_);
  }
}}
}