code: def parent_callback(self, parent_fu):
          
          if parent_fu.done() is True:
              e = parent_fu._exception
              if e:
                  super().set_exception(e)
              else:
                  super().set_result(self.file_obj)
          return
docs: Callback from executor future to update the parent.
  
          Args:
              - parent_fu (Future): Future returned by the executor along with callback
  
          Returns:
              - None
  
          Updates the super() with the result() or exception()