title: learning python and also trying to implement scrapy ..getting this error
body: <p>I am going through the scrapy tutorial <a href="http://doc.scrapy.org/en/latest/intro/tutorial.html">http://doc.scrapy.org/en/latest/intro/tutorial.html</a>
  and I followed it till I ran this command</p>
  
  <pre><code>scrapy crawl dmoz
  </code></pre>
  
  <p>And it gave me output with an error</p>
  
  <pre><code>2013-08-25 13:11:42-0700 [scrapy] INFO: Scrapy 0.18.0 started (bot: tutorial)
  2013-08-25 13:11:42-0700 [scrapy] DEBUG: Optional features available: ssl, http11
  2013-08-25 13:11:42-0700 [scrapy] DEBUG: Overridden settings: {'NEWSPIDER_MODULE': 'tutorial.spiders', 'SPIDER_MODULES': ['tutorial.spiders'], 'BOT_NAME': 'tutorial'}
  2013-08-25 13:11:42-0700 [scrapy] DEBUG: Enabled extensions: LogStats, TelnetConsole, CloseSpider, WebService, CoreStats, SpiderState
  Traceback (most recent call last):
    File "/usr/local/bin/scrapy", line 4, in &lt;module&gt;
      execute()
    File "/Library/Python/2.7/site-packages/scrapy/cmdline.py", line 143, in execute
      _run_print_help(parser, _run_command, cmd, args, opts)
    File "/Library/Python/2.7/site-packages/scrapy/cmdline.py", line 88, in _run_print_help
      func(*a, **kw)
    File "/Library/Python/2.7/site-packages/scrapy/cmdline.py", line 150, in _run_command
      cmd.run(args, opts)
    File "/Library/Python/2.7/site-packages/scrapy/commands/crawl.py", line 46, in run
      spider = self.crawler.spiders.create(spname, **opts.spargs)
    File "/Library/Python/2.7/site-packages/scrapy/command.py", line 34, in crawler
      self._crawler.configure()
    File "/Library/Python/2.7/site-packages/scrapy/crawler.py", line 44, in configure
      self.engine = ExecutionEngine(self, self._spider_closed)
    File "/Library/Python/2.7/site-packages/scrapy/core/engine.py", line 62, in __init__
      self.downloader = Downloader(crawler)
    File "/Library/Python/2.7/site-packages/scrapy/core/downloader/__init__.py", line 73, in __init__
      self.handlers = DownloadHandlers(crawler)
    File "/Library/Python/2.7/site-packages/scrapy/core/downloader/handlers/__init__.py", line 18, in __init__
      cls = load_object(clspath)
    File "/Library/Python/2.7/site-packages/scrapy/utils/misc.py", line 38, in load_object
      mod = __import__(module, {}, {}, [''])
    File "/Library/Python/2.7/site-packages/scrapy/core/downloader/handlers/s3.py", line 4, in &lt;module&gt;
      from .http import HTTPDownloadHandler
    File "/Library/Python/2.7/site-packages/scrapy/core/downloader/handlers/http.py", line 5, in &lt;module&gt;
      from .http11 import HTTP11DownloadHandler as HTTPDownloadHandler
    File "/Library/Python/2.7/site-packages/scrapy/core/downloader/handlers/http11.py", line 13, in &lt;module&gt;
      from scrapy.xlib.tx import Agent, ProxyAgent, ResponseDone, \
    File "/Library/Python/2.7/site-packages/scrapy/xlib/tx/__init__.py", line 6, in &lt;module&gt;
      from . import client, endpoints
    File "/Library/Python/2.7/site-packages/scrapy/xlib/tx/client.py", line 37, in &lt;module&gt;
      from .endpoints import TCP4ClientEndpoint, SSL4ClientEndpoint
    File "/Library/Python/2.7/site-packages/scrapy/xlib/tx/endpoints.py", line 222, in &lt;module&gt;
      interfaces.IProcessTransport, '_process')):
    File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/zope/interface/declarations.py", line 495, in __call__
      raise TypeError("Can't use implementer with classes.  Use one of "
  TypeError: Can't use implementer with classes.  Use one of the class-declaration functions instead.
  </code></pre>
  
  <p>I am not very familiar with python and I am not sure what is it complaining about</p>
  
  <p>here is my domz_spider.py file</p>
  
  <pre><code>from scrapy.spider import BaseSpider
  
  class DmozSpider(BaseSpider):
      name = "dmoz"
      allowed_domains = ["dmoz.org"]
      start_urls = [
          "http://www.dmoz.org/Computers/Programming/Languages/Python/Books/",
          "http://www.dmoz.org/Computers/Programming/Languages/Python/Resources/"
      ]
  
      def parse(self, response):
          filename = response.url.split("/")[-2]
          open(filename, 'wb').write(response.body)
  
  And here is my items file
  
  # Define here the models for your scraped items
  #
  # See documentation in:
  # http://doc.scrapy.org/en/latest/topics/items.html
  
  from scrapy.item import Item, Field
  
      class DmozItem(Item):
          title = Field()
          link = Field()
          desc = Field()
  </code></pre>
  
  <p>and here is the directory structure</p>
  
  <pre><code>scrapy.cfg
  tutorial/
  tutorial/items.py
  tutorial/pipelines.py
  tutorial/settings.py
  tutorial/spiders/
  tutorial/spiders/domz_spider.py
  </code></pre>
  
  <p>here is the settings.py file</p>
  
  <pre><code>    BOT_NAME = 'tutorial'
  
      SPIDER_MODULES = ['tutorial.spiders']
      NEWSPIDER_MODULE = 'tutorial.spiders'
  </code></pre>