from prefect import flow, task
from datetime import date

@task(retries=3, retry_delay_seconds=10)
def extract(d): return f"raw({d})"

@task
def transform(raw): return raw.replace("raw","clean")

@task
def load(clean): print(f"loaded: {clean}")

@flow
def etl_flow(d: str | None = None):
    d = d or date.today().isoformat()
    load(transform(extract(d)))

if __name__ == "__main__":
    etl_flow()