In a letter to a friend where he was offering advice on how to write out plots, Anton Chekhov wrote “Remove everything that has no relevance to the story. If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it's not going to be fired, it shouldn't be hanging there.” It is the earliest recorded notion of the artistic notion of “Chekhov’s Gun”. The gun must go off; the setup must have a punchline; the pledge must be followed by the turn which is followed by the prestige. When we learn that Daenerys Targaryen owns dragon eggs we know that before too long there will be dragons. When Ripley shows she can use a robotic exoskeleton we know she’s going to use one to kill an Alien. When Brad Wesley’s goon is just driving around with a monster truck, you know it’s going to crush a car dealership before Dalton leaves town.