throws Throwable
  public Value evalNew(Env env, Expr []args)    throws Throwable  {    Value object = _classDef.evalNew(env, args);    if (object != null)      return object;        object = newInstance(env);    AbstractFunction fun = findConstructor();    if (fun != null) {      fun.evalMethod(env, object, args);    }    return object;  }