env.error(L.l("'{0}' is an unknown function.", _name));
env.error(getLocationLine(), L.l("'{0}' is an unknown function.", _name));
  private Value evalImpl(Env env, boolean isRef, boolean isCopy)  {    AbstractFunction fun = env.findFunction(_name);    if (fun == null) {      env.error(L.l("'{0}' is an unknown function.", _name));      return NullValue.NULL;    }    Value []args = fun.evalArguments(env, this, _args);    env.pushCall(this, NullValue.NULL);    try {      env.checkTimeout();	      if (isRef)	return fun.callRef(env, args);      else if (isCopy)	return fun.callCopy(env, args);      else	return fun.call(env, args);    } finally {      env.popCall();    }  }