i.e. make task a an implicit dependency of task b, even though no data flows from a to b

Hi @David Hogarty, you definitely can! For that you can use the

upstream_tasks

kwarg, which will explicitly set that dependency. You can read more about it here.

how do I use that within the functional api?

Hi David! If you want to operate within the functional API, you can also use

task.set_upstream

to explicitly define which tasks are upstream and downstream of each other. https://docs.prefect.io/api/latest/core/task.html#task-2

roger, so when I have a @prefect.task

Yep, you have a couple of options here. You can explicitly declare tasks and upstream/downstream dependencies like this naive example:

f = Flow(name="test")
t1 = Task()
t2 = Task()
t2.set_upstream(t1, flow=f)

or you can pass them in as arguments, like in this example:

with Flow("Example Flow") as flow:
    task_a = task_a()
    task_b = task_b(upstream_tasks=[task_a])

It really just depends on your style and use case. Sounds like you're on the right track, but don't hesitate to reach out if you have any more questions!