def assert_correct_timestamp(self, html: str) -> None:
        """Extract the time stamp from `html`, and assert it is recent."""
        timestamp_pat = r"created at (\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2})"
        m = re.search(timestamp_pat, html)
        assert m, "Didn't find a time stamp!"
        timestamp = datetime.datetime(*[int(v) for v in m.groups()])    # type: ignore[arg-type]
        # The time stamp only records the minute, so the delta could be from
        # 12:00 to 12:01:59, or two minutes.
        self.assert_recent_datetime(
            timestamp,
            seconds=120,
            msg=f"Time stamp is wrong: {timestamp}",
        )
Extract the time stamp from `html`, and assert it is recent.
tests/test_html.py