usable_importers = importers where can_handle(input_file) returns true

  for importer_class in usable_importers:

    input_file.seek(0)

    for entry_data in importer_class(input_file):

      for hook in all_hooks:

          break

        elif hook_return is not None:

          entry_data = hook_return

Note in particular that multiple importers can handle the same input file.  This helps support inputs like Patreon's earnings CSV, where completely different transactions are generated from the same source.