code: def next_page(self):
          
          try:
              next_url = self.next_url
          except AttributeError:
              raise PageError("Page %r has no next page" % self)
          return self.page_for_url(next_url)
docs: Return the next `Page` after this one in the result sequence
          it's from.
  
          If the current page is the last page in the sequence, calling
          this method raises a `ValueError`.