code: def find_link(self, href_pattern, make_absolute=True):
          
  
          if make_absolute:
              self.tree.make_links_absolute(self.doc.url)
  
          if isinstance(href_pattern, six.text_type):
              raise GrabMisuseError('Method `find_link` accepts only '
                                    'byte-string argument')
          href_pattern = make_unicode(href_pattern)
          for elem, _, link, _ in self.tree.iterlinks():
              if elem.tag == 'a' and href_pattern in link:
                  return link
          return None
docs: Find link in response body which href value matches ``href_pattern``.
  
          Returns found url or None.