1try:
2    import usocket as socket, uselect as select, uerrno as errno
3except ImportError:
4    try:
5        import socket, select, errno
6
7        select.poll  # Raises AttributeError for CPython implementations without poll()
8    except (ImportError, AttributeError):
9        print("SKIP")
10        raise SystemExit
11
12
13poller = select.poll()
14
15s = socket.socket()
16
17poller.register(s)
18# https://docs.python.org/3/library/select.html#select.poll.register
19# "Registering a file descriptor that’s already registered is not an error,
20# and has the same effect as registering the descriptor exactly once."
21poller.register(s)
22
23# 2 args are mandatory unlike register()
24try:
25    poller.modify(s)
26except TypeError:
27    print("modify:TypeError")
28
29poller.modify(s, select.POLLIN)
30
31poller.unregister(s)
32
33try:
34    poller.modify(s, select.POLLIN)
35except OSError as e:
36    assert e.args[0] == errno.ENOENT
37
38# poll after closing the socket, should return POLLNVAL
39poller.register(s)
40s.close()
41p = poller.poll(0)
42print(len(p), p[0][-1])
43