# Chained celery tasks with delay

Leverage [Celery Chains](https://docs.celeryq.dev/en/stable/userguide/canvas.html#chains) to execute sequential tasks. But it wasn't clear from the documentation on how to add a delay in-between executions.

The initial (reasonable) attempt:

```python
result = (
  add.s(1,1) |
  mul.s(3) | 
  mul.s(4)
).apply_async(countdown=5)  # 24
```

resulted in the task completing immediately.

However setting the `countdown` for each signature\* worked.

```python
result = (
  add.s(1,1) | 
  mul.s(3).set(countdown=5) | 
  mul.s(4).set(countdown=5)
) # 24
```

> \*use [immutable signatures](https://docs.celeryq.dev/en/stable/userguide/canvas.html#immutability) (shortcut: si) so the next task doesn't require the return value of the previous one who's result is implicitly passed as the first argument