'Analyze which references are cached by archive.org
:return: A list of query string objects for the URLs that are in
the cache AND are in the target web site.'

def _analyze_urls(self, references):

    real_urls = []
    for url in references:
        url = url.url_string[url.url_string.index('http', 1):]
        real_urls.append(URL(url))
    real_urls = list(set(real_urls))
    if len(real_urls):
        om.out.debug('Archive.org    cached    the    following    pages:')
        for u in real_urls:
            om.out.debug(('-    %s' % u))
    else:
        om.out.debug('Archive.org    did    not    find    any    pages.')
    self.worker_pool.map(self._exists_in_target, real_urls)
