boolean isValidMessage(String identifier) {
		return  "cantPick".equals(identifier) ||
				"cantTraverse".equals(identifier) ||
				"cantDo".equals(identifier) ||
				"didntUnderstand".equals(identifier) ||
				"pickedUp".equals(identifier) ||
				"emptyInventory".equals(identifier) ||
				"changedLocation".equals(identifier) ||
				"currentLocation".equals(identifier);
	}