Suppose you are having a party in half an hour and you have two 6-packs of beer in your refrigerator. One is an imported premium beer, and the other is a standard domestic beer. A neighbor comes to you and asks you to trade some imported premium beer for the standard domestic beer, because he is also having a party. You agree to trade two premium bottles for three standard bottles. Twenty minutes later, the neighbor comes back and asks for two more premium bottles. Will you still trade on a two premium bottles for three standard bottles basis? Suppose you demand four standard bottles for two premium bottles. What property of indifference curves is illustrated by this example