Task: Story Composition
Input (English): Premise: Edgar loved his family's mastiffs, but he wished for a horse. 
 Initial Context: He even wrote to Santa Claus asking for a horse ride for Christmas! 
 Original Ending: Edgar's dad had an idea for making that wish come true. On Christmas morning he set little Edgar on the largest dog. The dog let Edgar ride him just like a real horse! 
 Counterfactual Context: He even wrote to his Grandmother asking for a horse for his birthday.
Output (English): Edgar's grandmother had an idea for making that wish come true. On Christmas morning she set little Edgar on the largest dog. The dog let Edgar ride him just like a real horse!