title: replacement for return inside a generator
body: <p>I am trying to deploy a Scrapy spider to scraping,however, I wrote code in Python3 which <code>shub</code> doesn't allow, so I need to convert code to Python2.7</p>
  
  <pre><code>Deploy log last 30 lines:
      _get_apisettings, commands_module='sh_scrapy.commands')
    File "/usr/local/lib/python2.7/site-packages/sh_scrapy/crawl.py", line 148, in _run_usercode
      _run(args, settings)
    File "/usr/local/lib/python2.7/site-packages/sh_scrapy/crawl.py", line 103, in _run
      _run_scrapy(args, settings)
    File "/usr/local/lib/python2.7/site-packages/sh_scrapy/crawl.py", line 111, in _run_scrapy
      execute(settings=settings)
    File "/usr/local/lib/python2.7/site-packages/scrapy/cmdline.py", line 149, in execute
      cmd.crawler_process = CrawlerProcess(settings)
    File "/usr/local/lib/python2.7/site-packages/scrapy/crawler.py", line 251, in __init__
      super(CrawlerProcess, self).__init__(settings)
    File "/usr/local/lib/python2.7/site-packages/scrapy/crawler.py", line 137, in __init__
      self.spider_loader = _get_spider_loader(settings)
    File "/usr/local/lib/python2.7/site-packages/scrapy/crawler.py", line 338, in _get_spider_loader
      return loader_cls.from_settings(settings.frozencopy())
    File "/usr/local/lib/python2.7/site-packages/scrapy/spiderloader.py", line 61, in from_settings
      return cls(settings)
    File "/usr/local/lib/python2.7/site-packages/scrapy/spiderloader.py", line 25, in __init__
      self._load_all_spiders()
    File "/usr/local/lib/python2.7/site-packages/scrapy/spiderloader.py", line 47, in _load_all_spiders
      for module in walk_modules(name):
    File "/usr/local/lib/python2.7/site-packages/scrapy/utils/misc.py", line 71, in walk_modules
      submod = import_module(fullpath)
    File "/usr/local/lib/python2.7/importlib/__init__.py", line 37, in import_module
      __import__(name)
    File "/app/__main__.egg/niceprice/spiders/example.py", line 114
  SyntaxError: 'return' with argument inside generator
  {"message": "shub-image-info exit code: 1", "details": null, "error": "image_info_error"}
  </code></pre>
  
  <p>it is because of this line in spider</p>
  
  <pre><code>    def prase_item(self,response):
          if search('&amp;WS=\d*',response.request.url):
              return 0
  </code></pre>
  
  <p>Is there an equivalent way in achieving this,I tried yielding <code>None</code> but it break my pipelines.
  I used <code>return</code> because I don't want anything to be yielded (stop this iteration from continuing) </p>