def tostring(self, fully_qualified=True, pretty_print=True, encoding="UTF-8"):
        """
        Serialize and return a string of this METS document.

        To write to file, see :meth:`write`.

        The default encoding is ``UTF-8``. This method will return a unicode
        string when ``encoding`` is set to ``unicode``.

        :return: String of this document
        """
        root = self.serialize(fully_qualified=fully_qualified)
        kwargs = {"pretty_print": pretty_print, "encoding": encoding}
        if encoding != "unicode":
            kwargs["xml_declaration"] = True
        return etree.tostring(root, **kwargs)
Serialize and return a string of this METS document.

        To write to file, see :meth:`write`.

        The default encoding is ``UTF-8``. This method will return a unicode
        string when ``encoding`` is set to ``unicode``.

        :return: String of this document