code: def append(self, newconfig):
          for attr_name in (
              'title', 'body', 'author', 'date',
              'strip', 'strip_id_or_class', 'strip_image_src',
              'single_page_link', 'single_page_link_in_feed',
              'next_page_link', 'http_header'
          ):
              current_set = getattr(self, attr_name)
              for val in getattr(newconfig, attr_name):
                  current_set.add(val)
              setattr(self, attr_name, current_set)
          for attr_name in (
              'parser', 'tidy', 'prune', 'autodetect_on_failure'
          ):
              if getattr(self, attr_name) is None:
                  if getattr(newconfig, attr_name) is None:
                      setattr(self, attr_name, self.defaults[attr_name])
                  else:
                      setattr(self, attr_name, getattr(newconfig, attr_name))
          if self.parser == 'libxml':
              self.parser = 'lxml'
          for attr_name in ('find_string', 'replace_string', ):
              getattr(self, attr_name).extend(getattr(newconfig, attr_name))
          if self.find_string:
              self.replace_patterns = zip(
                  self.find_string, self.replace_string)
          else:
              self.replace_patterns = None