Is there a good way to have a task generate two lists e g er

Question

Is there a good way to have a task generate two lists e g error items and a processed items as output and map each list to a different downstream task

Jeremiah · Answer

Hi < Jacques> You can index the output of a task like this

Jeremiah · Answer

```from prefect import task Flow task def two lists return list one 1 2 3 list two 101 102 103 task def add one x return x + 1 with Flow example as flow lists = two lists x = add one map lists list one y = add one map lists list two state = flow run assert state result x result == 2 3 4 assert state result y result == 102 103 104 ```

Jeremiah · Answer

My example returns a dictionary but if you return a list or tuple and index as `lists 0 lists 1 ` it ll also work

Avi A · Answer

this also works if you don t want to return a `dict` I use something similar in my flow ```both items = task that generates two lists returns two lists error items processed items = both items 0 both items 1 error items task map error items processed items task map processed items ```

Jacques · Answer

Awesome thanks guys What does this look like using the imperative api do I just do a `error items task set upstream two lists list one key= data mapped=True `

Jeremiah · Answer

Yep

Jacques · Answer

Nice thanks