Multiple label per input with data block api

I am doing Multi Tasking Learning with fast ai v1 and I am looking a way to use the data block API with multiple label (can be FloatList, CategoryList, MultiCategoryList at the same time) per input. I successfully wrote a custom ItemList class and the method for creating the model but I am having trouble mapping the input to the label.
I know that I should write a custom class for the label but which one should I subclass LabelLists or LabelList?
What is the role of the PreProcessor and how is it called?

Thank you.


have you solve the problem of [Multiple label per input with data block api], can you tell me how to do it please.

Hello, I also want to do the same thing, did anyone solved it ?