code: def add_cookie_header(self, request, referrer_host=None):
          '''Wrapped ``add_cookie_header``.
  
          Args:
              request: An instance of :class:`.http.request.Request`.
              referrer_host (str): An hostname or IP address of the referrer
                  URL.
          '''
          new_request = convert_http_request(request, referrer_host)
          self._cookie_jar.add_cookie_header(new_request)
  
          request.fields.clear()
  
          for name, value in new_request.header_items():
              request.fields.add(name, valuef add_cookie_header(self, request, referrer_host=None):
          '''Wrapped ``add_cookie_header``.
  
          Args:
              request: An instance of :class:`.http.request.Request`.
              referrer_host (str): An hostname or IP address of the referrer
                  URL.
          '''
          new_request = convert_http_request(request, referrer_host)
          self._cookie_jar.add_cookie_header(new_request)
  
          request.fields.clear()
  
          for name, value in new_request.header_items():
              request.fields.add(name, value)
docs: Wrapped ``add_cookie_header``.
  
          Args:
              request: An instance of :class:`.http.request.Request`.
              referrer_host (str): An hostname or IP address of the referrer
                  URL.