public void fire(Player player, Sentence sentence, EventRaiser npc) {
int fee = TradingUtility.calculateFee(player, price).intValue();
if (TradingUtility.canPlayerAffordTradingFee(player, price)) {
if (createOffer(player, item, price, quantity)) {
TradingUtility.substractTradingFee(player, price);
new AsynchronousProgramExecutor("trade", buildTweetMessage(item, quantity, price)).start();
npc.say("I added your offer to the trading center and took the fee of "+ fee +".");
npc.setCurrentState(ConversationStates.ATTENDING);
} else {
npc.say("You don't have " + Grammar.quantityplnoun(quantity, item.getName(), "a") + ".");
}