Task: Story Composition
Input (English): Premise: Tim was waiting for the mail. 
 Initial Context: It never came. 
 Original Ending: Tim wondered why. Then he saw the calendar. It was Sunday so there would be no mail. 
 Counterfactual Context: It finally came.
Output (English): Tim wondered why it had taken so long. Then he saw the calendar. It was a holiday the day before, so mail was backed up.