Passing two datasets to `map_batches`

What’s the recommended way of combining data from two datasets in a function using map_batches?

Basically, my function would have the following format:
def fn(batch1: pd.DataFrame, batch2: pd.DataFrame) -> pd.DataFrame:

I couldn’t find any reference to this usecase in the docs. Did I miss anything or Ray pipelines aren’t supposed to support that?

Thank you in advance!