def __init__(self, title, *sections):
        """Create a new `Document` with `title` and zero or more `sections`.

        :param title: the tile of the document (`Document` or `Element` type)
        :param sections: document sections (`Document` or `Element` type)

        """
        self._title = promote_to_string(title)
        self._sections = [promote_to_string(s) for s in sections]