/** Visit class 'TupleLiteralExp' */
 public Object visit(TupleLiteralExp host, Object data) {
   String result = "Tuple {";
   // --- add all properties ---
   Iterator i = host.getTuplePart().iterator();
   while (i.hasNext()) {
     VariableDeclaration var = (VariableDeclaration) i.next();
     result += (String) var.accept(this, data);
     if (i.hasNext()) result += ", ";
   }
   result += "}";
   return result;
 }