def toTag(self, output):
        ''' This methods returns all data of this feed as feed xml tag

        :param output: XML Document to which the data should be added
        :type output: xml.dom.DOMImplementation.createDocument
        '''
        feed = output.createElement('feed')
        feed.setAttribute('name', self.name)
        feed.setAttribute('priority', str(self.priority))

        # schedule
        schedule = output.createElement('schedule')
        schedule.setAttribute('dayOfMonth', self.dayOfMonth)
        schedule.setAttribute('dayOfWeek', self.dayOfWeek)
        schedule.setAttribute('hour', self.hour)
        schedule.setAttribute('minute', self.minute)
        if self.retry:
            schedule.setAttribute('retry', self.retry)
        feed.appendChild(schedule)

        # url
        url = output.createElement('url')
        url.appendChild(output.createTextNode(self.url))
        feed.appendChild(url)

        # source
        if self.source:
            source = output.createElement('source')
            source.appendChild(output.createTextNode(self.source))
            feed.appendChild(source)
        return feed
This methods returns all data of this feed as feed xml tag

        :param output: XML Document to which the data should be added
        :type output: xml.dom.DOMImplementation.createDocument