code: def _extract_language(self):
          
  
          if self.language:
              return
  
          found = False
  
          for pattern in self.config.language:
              for item in self.parsed_tree.xpath(pattern):
                  stripped_language = item.strip()
  
                  if stripped_language:
                      self.language = stripped_language
                      LOGGER.info(u'Language extracted: %s.', stripped_language,
                                  extra={'siteconfig': self.config.host})
                      found = True
                      break
  
              if found:
                  break
docs: Extract language from the HTML ``<head>`` tags.