code: def process_spider_output(self, response, result, spider):
          '''
          Ensures the meta data from the response is passed
          through in any Request's generated from the spider
          '''
          self.logger.debug("processing meta passthrough middleware")
          for x in result:
              # only operate on requests
              if isinstance(x, Request):
                  self.logger.debug("found request")
                  # pass along all known meta fields, only if
                  # they were not already set in the spider's new request
                  for key in list(response.meta.keys()):
                      if key not in x.meta:
                          x.meta[key] = response.meta[key]
              yield f process_spider_output(self, response, result, spider):
          '''
          Ensures the meta data from the response is passed
          through in any Request's generated from the spider
          '''
          self.logger.debug("processing meta passthrough middleware")
          for x in result:
              # only operate on requests
              if isinstance(x, Request):
                  self.logger.debug("found request")
                  # pass along all known meta fields, only if
                  # they were not already set in the spider's new request
                  for key in list(response.meta.keys()):
                      if key not in x.meta:
                          x.meta[key] = response.meta[key]
              yield x
docs: Ensures the meta data from the response is passed
          through in any Request's generated from the spider