code: def override_start_requests(spider_cls, start_urls, callback=None, **attrs):
      
      def start_requests():
          for url in start_urls:
              req = Request(url, dont_filter=True) if isinstance(url, six.string_types) else url
              if callback is not None:
                  req.callback = callback
              yield req
      attrs['start_requests'] = staticmethod(start_requests)
      return type(spider_cls.__name__, (spider_cls, ), attrs)
docs: Returns a new spider class overriding the ``start_requests``.
  
      This function is useful to replace the start requests of an existing spider
      class on runtime.
  
      Parameters
      ----------
      spider_cls : scrapy.Spider
          Spider class to be used as base class.
      start_urls : iterable
          Iterable of URLs or ``Request`` objects.
      callback : callable, optional
          Callback for the start URLs.
      attrs : dict, optional
          Additional class attributes.
  
      Returns
      -------
      out : class
          A subclass of ``spider_cls`` with overrided ``start_requests`` method.