text: Title: add an example for processing independent chunks
  Body: This is a recurrent pattern and a few users have asked us about it so we should have a working example.
  
  Assume you're getting data on batches, users want to pass the batch through the full pipeline when the next batch arrives, they want to repeat the process. An extension of this problem is when they already have all the batches and want to process them in parallel. Note that this is different from the `grid` feature because this will process all batches at once. What we want here, is essentially a giant for loop (one per batch) where the loop runs the full pipeline for each batch.