code: def execute(self, task):
          
          try:
              return task.run()
          except Exception:
              if task.retries > 0:
                  task.retries -= 1
                  task.to_retrying()
  
                  if task.async:
                      # Place it back on the queue.
                      data = task.serialize()
                      task.task_id = self.backend.push(
                          self.queue_name,
                          task.task_id,
                          data
                      )
                  else:
                      return self.execute(task)
              else:
                  raise
docs: Given a task instance, this runs it.
  
          This includes handling retries & re-raising exceptions.
  
          Ex::
  
              task = Task(async=False, retries=5)
              task.to_call(add, 101, 35)
              finished_task = gator.execute(task)
  
          :param task_id: The identifier of the task to process
          :type task_id: string
  
          :returns: The completed ``Task`` instance