title: scrapy XMLFeedSpider parse xml group indicator
body: <p>I have some problem with xpath selector in Scrapy. I can't parse media tag. Can you help me, some ideas, some example code. Thanks
  This ys my spider</p>
  
  <pre><code>import scrapy
  from scrapy.spiders import XMLFeedSpider
  from crawler.items import News
  
  class CNNSpider(XMLFeedSpider):
      name = "cnn"
      start_urls = [
          'http://rss.cnn.com/rss/edition.rss', # Top stories
          #'http://rss.cnn.com/rss/cnn_latest.rss', # most recerent
      ]
      iterator = 'iternodes'  # This is actually unnecessary, since it's the default value
      itertag = 'item'
  
      def parse_node(self, response, node):
          item = News()
          item['title'] = node.xpath('./title/text()').extract()
          item['description'] = node.xpath('./description/text()').extract()
          item['link'] = node.xpath('./link/text()').extract()
          item['media'] = node.xpath("./media:group/media:content/@url").extract()
          item['pubDate'] = node.xpath('./pubDate/text()').extract()
          print item['media']
  </code></pre>
  
  <p>And my xml feed:</p>
  
  <pre><code>&lt;item&gt;
      &lt;title&gt;&lt;![CDATA[More than 200 dead in Mexico quake, buildings toppled]]&gt;&lt;/title&gt;
      &lt;link&gt;http://www.cnn.com/collections/mexico-city-earthquake-intl/&lt;/link&gt;
      &lt;guid isPermaLink="true"&gt;http://www.cnn.com/collections/mexico-city-earthquake-intl/&lt;/guid&gt;
      &lt;pubDate&gt;Wed, 20 Sep 2017 10:03:24 GMT&lt;/pubDate&gt;
      &lt;media:group&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-super-169.jpg" height="619" width="1100" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-large-11.jpg" height="300" width="300" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-vertical-large-gallery.jpg" height="552" width="414" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-video-synd-2.jpg" height="480" width="640" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-live-video.jpg" height="324" width="576" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-t1-main.jpg" height="250" width="250" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-vertical-gallery.jpg" height="360" width="270" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-story-body.jpg" height="169" width="300" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-t1-main.jpg" height="250" width="250" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-assign.jpg" height="186" width="248" /&gt;
          &lt;media:content medium="image" url="http://i2.cdn.turner.com/cnnnext/dam/assets/170919190244-25-mexico-earthquake-0919-hp-video.jpg" height="144" width="256" /&gt;
      &lt;/media:group&gt;
  &lt;/item&gt;
  </code></pre>