old_contents: """This may seem like a silly module right now, but we had to
  separate this out so that deferrable.py and its sub-modules
  could all import it without circular imports."""
  
  MAXIMUM_DELAY_SECONDS = 900
  
new_contents: """This may seem like a silly module right now, but we had to
  separate this out so that deferrable.py and its sub-modules
  could all import it without circular imports."""
  
  # SQS has a hard limit of 900 seconds, and Dockets
  # delay queues incur heavy performance penalties,
  # so this seems like a reasonable limit for all
  MAXIMUM_DELAY_SECONDS = 900
  
subject: Add back some reasoning on the 900 number