if (!hasMemo("talkBarman"))
{
  setMemo("talkBarman");
  return "default";
}
if (hasMemo("gotBeer"))
{
  return "default";
}
else
{
  if (itemCount("Coin") >= 1)
  {
    if (useItem("Potion"))
    {
      useItem("Coin");
      setMemo("gotBeer");
      // TODO: Give beer
      return "selling";
    }
    return "need_bottle";
  }
  return "need_coin";
}