Method override to create self-closing elements.

        https://docs.djangoproject.com/en/2.0/ref/utils/#django.utils.feedgenerator.SyndicationFeed.write
        https://github.com/django/django/blob/2.0/django/utils/feedgenerator.py#L216

def write(self, outfile, encoding):
        """Method override to create self-closing elements.

        https://docs.djangoproject.com/en/2.0/ref/utils/#django.utils.feedgenerator.SyndicationFeed.write
        https://github.com/django/django/blob/2.0/django/utils/feedgenerator.py#L216
        """
        try:
            handler = EscapeFriendlyXMLGenerator(outfile, encoding, short_empty_elements=True)
        except TypeError:  # Python 2
            handler = EscapeFriendlyXMLGenerator(outfile, encoding)
        handler.startDocument()
        handler.startElement('rss', self.rss_attributes())
        handler.startElement('channel', self.root_attributes())
        self.add_root_elements(handler)
        self.write_items(handler)
        self.endChannelElement(handler)
        handler.endElement('rss')