<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def url_permutations(url):
 """Try all permutations of hostname and path which can be applied to blacklisted URLs """

        def url_host_permutations(host):
            if re.match(r'\d+\.\d+\.\d+\.\d+', host):
                yield host
                return
            parts = host.split('.')
            l = min(len(parts), 5)
            if l > 4:
                yield host
            for i in range(l - 1):
                yield '.'.join(parts[i - l:])

        def url_path_permutations(path):
            yield path
            query = None
            if '?' in path:
                path, query = path.split('?', 1)
            if query is not None:
                yield path
            path_parts = path.split('/')[0:-1]
            curr_path = ''
            for i in range(min(4, len(path_parts))):
                curr_path = curr_path + path_parts[i] + '/'
                yield curr_path

        protocol, address_str = urllib.splittype(url)
        host, path = urllib.splithost(address_str)
        user, host = urllib.splituser(host)
        host, port = urllib.splitport(host)
        host = host.strip('/')
        seen_permutations = set()
        for h in url_host_permutations(host):
            for p in url_path_permutations(path):
                u = '{}{}'.format(h, p)
                if u not in seen_permutations:
                    yield u
                    seen_permutations.add(u)