How to use the distutils2.pypi.simple.Crawler function in Distutils2

def to_nix_dict(egg, nixname):
    """Return a dict of the package attributes relevant to a nix
    expression
    """
    pypi = Crawler()

    name = egg['name']
    if egg['extras']:
        name += '-'.join(egg['extras'])
    name += '-' + egg['version']

    version = suggest_normalized_version(egg['version'])
    egg_release = pypi.get_release(egg['name'] + '==' + version)
    egg_dist = egg_release.dists['sdist'].url
    url = egg_dist['url']
    url = url.replace("http://a.pypi", "http://pypi")
    url = url.replace(name, "${name}")

    build_inputs = ''
    if url.endswith(".zip"):
        build_inputs = "\n    buildInputs = [ pkgs.unzip ];\n"

An index can be specified using -i or --index-url followed by an address.
    You can specify -v or --version followed by a specific version number and
    search will return the closest match.
    
    In the future it will be changed to an expression so instead of returning a single
    match, it will return multiple and you can use an expression like >0.6.3,!=0.8.3,<=1.0.2
    to get all versions greater then 0.6.3 not 0.8.3 and all less then or equal to 1.0.2
    """
    
    #search returns a ReleasesList which is a list of ReleaseInfo's
    from distutils2.pypi.dist import ReleasesList, ReleaseInfo
    from distutils2.pypi.simple import Crawler
    
    #no index specified, use standard
    if not args.index_url:
        crawler = Crawler()
    #use custom index
    else:
        if isinstance(args.index_url, str):
            crawler = Crawler(index_url = args.index_url)
        else:
            print('--index-url must be a string')
            return
    
    print("Recieved {0}".format(args))
    
    print("---------- Search Results ----------")
    #search!
    if not args.version:
        releaseList = crawler.get_releases(args.package_name)
        releaseList.sort_releases(reverse = False)

In the future it will be changed to an expression so instead of returning a single
    match, it will return multiple and you can use an expression like >0.6.3,!=0.8.3,<=1.0.2
    to get all versions greater then 0.6.3 not 0.8.3 and all less then or equal to 1.0.2
    """
    
    #search returns a ReleasesList which is a list of ReleaseInfo's
    from distutils2.pypi.dist import ReleasesList, ReleaseInfo
    from distutils2.pypi.simple import Crawler
    
    #no index specified, use standard
    if not args.index_url:
        crawler = Crawler()
    #use custom index
    else:
        if isinstance(args.index_url, str):
            crawler = Crawler(index_url = args.index_url)
        else:
            print('--index-url must be a string')
            return
    
    print("Recieved {0}".format(args))
    
    print("---------- Search Results ----------")
    #search!
    if not args.version:
        releaseList = crawler.get_releases(args.package_name)
        releaseList.sort_releases(reverse = False)
        
        #display the results!
        for release in releaseList:
            print('\nName   : {0}'.format(release.name))
            print('Version: {0}'.format(release.version))

#ignore_packages = ['plone_recipe_zope2instance',]
ignore_packages = []

install_command = """
    # ignore dependencies
    installCommand = ''
      easy_install --always-unzip --no-deps --prefix="$out" .
    '';
"""


plonedeps = open("plonedeps", "r").read()
if __name__ == '__main__':
    #eggs = to_dict(sys.stdin.read())
    eggs = to_dict(plonedeps)
    pypi = Crawler()

    bad_eggs = []
    not_found = []
    version_error = []
    print PRE_TMPL

    for nixname in sorted(eggs.keys()):
        if nixname in system_packages: continue
        if nixname in ignore_packages: continue
        egg = eggs[nixname]
        version = suggest_normalized_version(egg['version'])
        name = egg['name']
        if egg['extras']:
            name += '-'.join(egg['extras'])
        name += '-' + egg['version']
        if version is None: