code: def append(self, request, response):
          
          request = self._before_record_request(request)
          if not request:
              return
          # Deepcopy is here because mutation of `response` will corrupt the
          # real response.
          response = copy.deepcopy(response)
          response = self._before_record_response(response)
          if response is None:
              return
          self.data.append((request, response))
          self.dirty = True
docs: Add a request, response pair to this cassette