from prefect import Flow, task, unmapped
import prefect

@task
def retrieve_episode_ids():
    return [1,2,3,4,5]

@task()
def reduce(x, y):
    return x

with Flow("import_episodes") as flow:
    episode_ids = retrieve_episode_ids()
    reduce.map(episode_ids, y=unmapped("'test'"))

flow.run()