Task: Story Composition
Input (English): Premise: I've always wanted to ride on a river boat. 
 Initial Context: The kind with the big water wheel that went on the Mississippi river. 
 Original Ending: I saw one once in an old movie. I guess the water wheel doesn't change much but I bet it's more quiet. I'm saving my money to ride one if I ever get the chance. 
 Counterfactual Context: I'd never seem one before.
Output (English): I saw one once in an old movie. I guess the water wheel doesn't change much but I bet it's more quiet. I'm saving my money to ride one if I ever get the chance.