docs: def map(cls, sources, *, transform_args=None):
      """Generates instances from the sources using either cls.transform_args or transform_args
      argument if present.
      """
      for idx, source in enumerate(sources):
        try:
          yield cls.create(source, transform_args=transform_args)
        except Exception as ex:
          raise Exception("An error occurred with item {0}".format(idx)) from ex