Exercise 1 solution

    from datetime import datetime, date, time, timedelta, timezone
    from zoneinfo import ZoneInfo

    UTC = timezone.utc

    def resolve(d, t, zone):
        z = ZoneInfo(zone)
        return datetime.combine(d, t, tzinfo=z).astimezone(UTC).astimezone(z)

    def weekly(start, t, zone, weekdays, count):
        out, d = [], start
        while len(out) < count:
            if d.weekday() in weekdays:
                out.append(resolve(d, t, zone))
            d += timedelta(days=1)
        return out

    for o in weekly(date(2026, 10, 27), time(10), "America/New_York", {1, 3}, 6):
        u = o.astimezone(UTC)
        lon = o.astimezone(ZoneInfo("Europe/London"))
        print(o.strftime("%a %d %b %H:%M %Z"), "|", u.strftime("%H:%M UTC"), "|", lon.strftime("%H:%M %Z"))

Output (run, and exactly as shown):

    Tue 27 Oct 10:00 EDT | 14:00 UTC | 14:00 GMT
    Thu 29 Oct 10:00 EDT | 14:00 UTC | 14:00 GMT
    Tue 03 Nov 10:00 EST | 15:00 UTC | 15:00 GMT
    Thu 05 Nov 10:00 EST | 15:00 UTC | 15:00 GMT
    Tue 10 Nov 10:00 EST | 15:00 UTC | 15:00 GMT
    Thu 12 Nov 10:00 EST | 15:00 UTC | 15:00 GMT

Explanation: the rule is "10:00 in New York", so the wall time never changes
and the UTC instant does. The United States moved its clocks back on 1
November 2026, so 10:00 is UTC-4 (14:00 UTC) before that date and UTC-5
(15:00 UTC) after it. The United Kingdom had already moved back on 25
October, so for London the same meeting is 14:00 on both of the first two
dates (the gap between the two countries was one hour shorter than usual
for a week) and 15:00 afterwards, in step with New York. Generating each
occurrence from the local date and then converting, rather than adding 7
days to one UTC instant, is what keeps the meeting at 10:00 for the people
in New York.