title: Scrapy TabError: inconsistent use of tabs and spaces in indentation
body: <p>I want to use scrapy to crawl a website, just within the website, not external links.<br />
  here is what I've tried :</p>
  
  <pre><code>import scrapy
  import json
  import uuid
  import os
  from scrapy.linkextractors import LinkExtractor
  
  class ItemSpider(scrapy.Spider):
      name = "items"
      allowed_domains = ['https://www.website.com']
      start_urls = ['https://www.website.com/post']
      rules = (Rule(LxmlLinkExtractor(allow=()), callback='parse_obj', follow=True),)
      def parse_obj(self, response):
          for link in LxmlLinkExtractor(allow=self.allowed_domains).extract_links(response):
          response_obj = {}
          counter = 1
          for item in response.css(".category-lcd"):
              title = item.css("div.td-post-header &gt; header &gt; h1::text").extract()
              title_name = title[0]
              response_obj[counter] = {
                  'demo': item.css("div.td-post-content &gt; blockquote:nth-child(10) &gt; p::text").extract(),
                  'title_name': title_name,
                  'download_link': item.css("div.td-post-content &gt; blockquote:nth-child(12) &gt; p::text").extract()
              }
              counter += 1
          filename =  str(uuid.uuid4()) + ".json"
          with open(os.path.join('C:/scrapy/tutorial/results/',filename), 'w') as fp:
              json.dump(response_obj, fp)
  </code></pre>
  
  <p>But scraper doesn't work, What's wrong?!
  It says :</p>
  
  <blockquote>
    <p>Scrapy TabError: inconsistent use of tabs and spaces in indentation</p>
  </blockquote>