docs: def add(data, id, medium, credentials):
      """Adds the [medium] with the given id and data to the user's [medium]List.
      :param data   The data for the [medium] to add.
      :param id     The id of the data to add.
      :param medium Anime or manga (tokens.Medium.ANIME or tokens.Medium.MANGA).
      :raise ValueError For bad arguments.
      """
      _op(data, id, medium, tokens.Operations.ADD, credentials)