An ice cream shop made the best pistachio ice cream around. It was the only flavour of ice cream it made. For years it sold well but one day sales started to decline. Some of the customers told the shop owner they should think of serving different flavours. But pistachio had sold well for years so the ice cream shop continued to make only pistachio. The ice cream shop told its customers that if they didn’t buy more pistachio ice cream, the shop would go out of business and they’d never again taste their pistachio ice cream. Some of…