Return XML serialization of this list.

        If this list can be serialized as a single sitemap then the
        superclass method is used.

        If there is no single XML serialization (in the case that the
        number of list resources is more than is allowed in a single sitemap)
        then raise an exception unless allow_multifile is set True.
        If allow_multifile is set True then will return the sitemapindex
        for the set of component sitemaps.

def as_xml(self, allow_multifile=False, basename="/tmp/sitemap.xml"):
        """Return XML serialization of this list.

        If this list can be serialized as a single sitemap then the
        superclass method is used.

        If there is no single XML serialization (in the case that the
        number of list resources is more than is allowed in a single sitemap)
        then raise an exception unless allow_multifile is set True.
        If allow_multifile is set True then will return the sitemapindex
        for the set of component sitemaps.
        """
        if (not self.requires_multifile()):
            return super(ListBaseWithIndex, self).as_xml()
        elif (allow_multifile):
            return self.as_xml_index(basename)
        else:
            raise ListBaseIndexError(
                "Attempt to write single XML string for list with %d entries when max_sitemap_entries is set to %d" %
                (len(self), self.max_sitemap_entries))