How to use the feedgenerator.RssFeed function in feedgenerator

handler.addQuickElement("description", self.feed['description'])
        handler.addQuickElement("atom:link", None, {"rel": "self", "href": self.feed['feed_url']})
        if self.feed['language'] is not None:
            handler.addQuickElement("language", self.feed['language'])
        for cat in self.feed['categories']:
            handler.addQuickElement("category", cat)
        if self.feed['feed_copyright'] is not None:
            handler.addQuickElement("copyright", self.feed['feed_copyright'])
        handler.addQuickElement("lastBuildDate", rfc2822_date(self.latest_post_date()).decode('utf-8'))
        if self.feed['ttl'] is not None:
            handler.addQuickElement("ttl", self.feed['ttl'])

    def endChannelElement(self, handler):
        handler.endElement("channel")

class RssUserland091Feed(RssFeed):
    _version = "0.91"
    def add_item_elements(self, handler, item):
        handler.addQuickElement("title", item['title'])
        handler.addQuickElement("link", item['link'])
        if item['description'] is not None:
            handler.addQuickElement("description", item['description'])

class Rss201rev2Feed(RssFeed):
    # Spec: http://blogs.law.harvard.edu/tech/rss
    _version = "2.0"
    def add_item_elements(self, handler, item):
        handler.addQuickElement("title", item['title'])
        handler.addQuickElement("link", item['link'])
        if item['description'] is not None:
            handler.addQuickElement("description", item['description'])

handler.addQuickElement("lastBuildDate", rfc2822_date(self.latest_post_date()).decode('utf-8'))
        if self.feed['ttl'] is not None:
            handler.addQuickElement("ttl", self.feed['ttl'])

    def endChannelElement(self, handler):
        handler.endElement("channel")

class RssUserland091Feed(RssFeed):
    _version = "0.91"
    def add_item_elements(self, handler, item):
        handler.addQuickElement("title", item['title'])
        handler.addQuickElement("link", item['link'])
        if item['description'] is not None:
            handler.addQuickElement("description", item['description'])

class Rss201rev2Feed(RssFeed):
    # Spec: http://blogs.law.harvard.edu/tech/rss
    _version = "2.0"
    def add_item_elements(self, handler, item):
        handler.addQuickElement("title", item['title'])
        handler.addQuickElement("link", item['link'])
        if item['description'] is not None:
            handler.addQuickElement("description", item['description'])

        # Author information.
        if item["author_name"] and item["author_email"]:
            handler.addQuickElement("author", "%s (%s)" % \
                (item['author_email'], item['author_name']))
        elif item["author_email"]:
            handler.addQuickElement("author", item["author_email"])
        elif item["author_name"]:
            handler.addQuickElement("dc:creator", item["author_name"], {"xmlns:dc": "http://purl.org/dc/elements/1.1/"})