def METHOD_NAME():
    hs = HourInterval(start_hour="00:00", stop_hour="06:30", freq="day")
    assert hs.start_hour == "00:00"
    assert hs.stop_hour == "06:30"
    assert hs.period.freq == "day"
    expr = hs.filter_timestamp_column(EventsCallsTable.datetime)
    expected = "to_char(events.calls.datetime, 'HH24:MI') >= '00:00' AND to_char(events.calls.datetime, 'HH24:MI') < '06:30'"
    assert expected == get_string_representation(expr)