URL: http://tycho.usno.navy.mil/cgi-bin/timer.pl is broken in the example 
https://docs.python.org/3/tutorial/stdlib.html#internet-access

> curl -v http://tycho.usno.navy.mil/cgi-bin/timer.pl
* Could not resolve host: tycho.usno.navy.mil
* Closing connection 0
curl: (6) Could not resolve host: tycho.usno.navy.mil

This seems to be a temporary outage, expected to be restored in the first half of 2022.  Source:  https://www.usno.navy.mil/USNO/time/master-clock

I'll look for an alternative time source that is currently online.

I'm thinking of this an a replacement example:

>>> import json
>>> import urllib.request
>>> url = "http://worldtimeapi.org/api/timezone/America/Los_Angeles"
>>> with urllib.request.urlopen(url) as response:
...     timeinfo = json.load(response)
...
>>> print(timeinfo['datetime'])
2021-12-30T21:32:08.588278-08:00

This is a little closer to the current code.  Also it has a simpler and more universal url.


from urllib.request import urlopen
url = 'http://worldtimeapi.org/api/timezone/etc/UTC.txt'
with urlopen(url) as request:
    for line in request:
        line = line.decode('utf-8')
        if line.startswith('datetime'):
            print(line)

datetime: 2021-12-31T08:23:15.083004+00:00

New changeset ac4eea21722d9ed1604c9c30a8d29ae2ce74f1b2 by Raymond Hettinger in branch 'main':
bpo-46079: Replace external link that is down for maintenance. (GH-30315)
https://github.com/python/cpython/commit/ac4eea21722d9ed1604c9c30a8d29ae2ce74f1b2

New changeset 2bd73546959619b2519a7a830b3aaf190abeaf78 by Miss Islington (bot) in branch '3.10':
bpo-46079: Replace external link that is down for maintenance. (GH-30315) (GH-30328)
https://github.com/python/cpython/commit/2bd73546959619b2519a7a830b3aaf190abeaf78

New changeset 72ffcb02f3ea6efcd3afe368996dc3ee89701898 by Miss Islington (bot) in branch '3.9':
bpo-46079: Replace external link that is down for maintenance. (GH-30315) (GH-30329)
https://github.com/python/cpython/commit/72ffcb02f3ea6efcd3afe368996dc3ee89701898