def retrieve_page(rurl = nil)
      durl = rurl || url
      return nil unless durl
      durl = filter_url(durl) if self.respond_to?(:filter_url)
      self.class.retrieve_session ||= WebPageParser::HTTP::Session.new
      encode(self.class.retrieve_session.get(durl))
    end
def retrieve_page(rurl = nil)
      durl = rurl || url
      return nil unless durl
      durl = filter_url(durl) if self.respond_to?(:filter_url)
      self.class.retrieve_session ||= WebPageParser::HTTP::Session.new
      encode(self.class.retrieve_session.get(durl))
    end
request the page from the server and return the raw contents