docs: def attach_tasks(self, tasks: Tasks):
          """Attach a set of tasks.
  
          A task cannot be scheduled or executed before it is attached to an
          Engine.
  
          >>> tasks = Tasks()
          >>> spin.attach_tasks(tasks)
          """
          if tasks._spin is not None and tasks._spin is not self:
              logger.warning('Tasks already attached to a different Engine')
          self._tasks.update(tasks)
          tasks._spin = self