A: What do you have for lunch, David?
B: I have a peanut butter and jelly sandwich.
A: That sounds good. I have tuna.
B: Tuna is good too, Daniel.
A: I like jelly. Do you want to trade?
B: Sure. I like tuna.
A: This trade is good for both of us.
B: Yes, it is. Thanks, Daniel.
