anchor.diff: -{ lib, stdenv
  +{ lib
  +, stdenv
   , buildPythonPackage
   , isPy27
   , fetchPypi
  
positive.code:     install -m 644 -D extras/scrapy_zsh_completion $out/share/zsh/site-functions/_scrapy
    '';
  
    meta = with lib; {
      description = "A fast high-level web crawling and web scraping framework, used to crawl websites and extract structured data from their pages";
      homepage = "https://scrapy.org/";
  
negative.code:     "test_retry_dns_error"
      "test_custom_asyncio_loop_enabled_true"
      "test_custom_loop_asyncio"
    ] ++ stdenv.lib.optionals stdenv.isDarwin [
      "test_xmliter_encoding"
      "test_download"
    ];
  
    src = fetchPypi {
      inherit pname version;
  