code: def clean_list(l0, clean_item_fn=None):
      
      clean_item_fn = clean_item_fn if clean_item_fn else clean_item
      l = list()
      for index, item in enumerate(l0):
          cleaned_item = clean_item_fn(item)
          l.append(cleaned_item)
      return l
docs: Return a json-clean list. Will log info message for failures.