How to use the pyowm.utils.timeformatutils.to_UNIXtime function in pyowm

def test_next_year(self):
        result = timeutils.next_year()
        expected = datetime.now() + timedelta(days=365)
        self.assertAlmostEqual(
            float(timeformatutils.to_UNIXtime(expected)),
            float(timeformatutils.to_UNIXtime(result)))

def test_last_week(self):
        result = timeutils.last_week()
        expected = datetime.now() + timedelta(days=-7)
        self.assertAlmostEqual(
           float(timeformatutils.to_UNIXtime(expected)),
           float(timeformatutils.to_UNIXtime(result)))

def test_last_week(self):
        result = timeutils.last_week()
        expected = datetime.now() + timedelta(days=-7)
        self.assertAlmostEqual(
           float(timeformatutils.to_UNIXtime(expected)),
           float(timeformatutils.to_UNIXtime(result)))

def test_next_hour(self):
        result = timeutils.next_hour()
        expected = datetime.now() + timedelta(hours=1)
        self.assertAlmostEqual(
           float(timeformatutils.to_UNIXtime(expected)),
           float(timeformatutils.to_UNIXtime(result)))

def test_next_year(self):
        result = timeutils.next_year()
        expected = datetime.now() + timedelta(days=365)
        self.assertAlmostEqual(
            float(timeformatutils.to_UNIXtime(expected)),
            float(timeformatutils.to_UNIXtime(result)))

def test_to_UNIXtime(self):
        unix = 1378459200
        iso = "2013-09-06 09:20:00+00"
        date = datetime(2013, 9, 6, 9, 20, 0, tzinfo=timeformatutils.UTC())
        self.assertEqual(unix, timeformatutils.to_UNIXtime(unix))
        self.assertEqual(unix, timeformatutils.to_UNIXtime(iso))
        self.assertEqual(unix, timeformatutils.to_UNIXtime(date))

cannot be parsed, *APICallException* when OWM web API can not be
            reached, *ValueError* if the time boundaries are not in the correct
            chronological order, if one of the time boundaries is not ``None``
            and the other is or if one or both of the time boundaries are after
            the current time

        """
        assert type(id) is int, "'id' must be an int"
        if id < 0:
            raise ValueError("'id' value must be greater than 0")
        params = {'id': id, 'lang': self._language}
        if start is None and end is None:
            pass
        elif start is not None and end is not None:
            unix_start = timeformatutils.to_UNIXtime(start)
            unix_end = timeformatutils.to_UNIXtime(end)
            if unix_start >= unix_end:
                raise ValueError("Error: the start time boundary must " \
                                 "precede the end time!")
            current_time = time()
            if unix_start > current_time:
                raise ValueError("Error: the start time boundary must " \
                                 "precede the current time!")
            params['start'] = str(unix_start)
            params['end'] = str(unix_end)
        else:
            raise ValueError("Error: one of the time boundaries is None, " \
                             "while the other is not!")
        uri = http_client.HttpClient.to_url(CITY_WEATHER_HISTORY_URL,
                                            self._API_key,
                                            self._subscription_type,
                                            self._use_ssl)

def get_alerts_since(self, timestamp):
        """
        Returns all the `Alert` objects of this `Trigger` that were fired since the specified timestamp.
        :param timestamp: time object representing the point in time since when alerts have to be fetched
        :type timestamp: int, ``datetime.datetime`` or ISO8601-formatted string
        :return: list of `Alert` instances
        """
        unix_timestamp = timeformatutils.to_UNIXtime(timestamp)
        result = []
        for alert in self.alerts:
            if alert.last_update >= unix_timestamp:
                result.append(alert)
        return result

:raises: *ParseResponseException* when OWM web API responses' data
            cannot be parsed, *APICallException* when OWM web API can not be
            reached, *ValueError* if the time boundaries are not in the correct
            chronological order, if one of the time boundaries is not ``None``
            and the other is or if one or both of the time boundaries are after
            the current time

        """
        assert type(id) is int, "'id' must be an int"
        if id < 0:
            raise ValueError("'id' value must be greater than 0")
        params = {'id': id, 'lang': self._language}
        if start is None and end is None:
            pass
        elif start is not None and end is not None:
            unix_start = timeformatutils.to_UNIXtime(start)
            unix_end = timeformatutils.to_UNIXtime(end)
            if unix_start >= unix_end:
                raise ValueError("Error: the start time boundary must " \
                                 "precede the end time!")
            current_time = time()
            if unix_start > current_time:
                raise ValueError("Error: the start time boundary must " \
                                 "precede the current time!")
            params['start'] = str(unix_start)
            params['end'] = str(unix_end)
        else:
            raise ValueError("Error: one of the time boundaries is None, " \
                             "while the other is not!")
        uri = http_client.HttpClient.to_url(CITY_WEATHER_HISTORY_URL,
                                            self._API_key,
                                            self._subscription_type,

not available for the specified location
        :raises: *ParseResponseException* when OWM web API responses' data
            cannot be parsed, *APICallException* when OWM web API can not be
            reached, *ValueError* if the time boundaries are not in the correct
            chronological order, if one of the time boundaries is not ``None``
            and the other is or if one or both of the time boundaries are after
            the current time

        """
        OWM25._assert_is_string("name", name)
        params = {'q': name, 'lang': self._language}
        if start is None and end is None:
            pass
        elif start is not None and end is not None:
            unix_start = timeformatutils.to_UNIXtime(start)
            unix_end = timeformatutils.to_UNIXtime(end)
            if unix_start >= unix_end:
                raise ValueError("Error: the start time boundary must "
                                 "precede the end time!")
            current_time = time()
            if unix_start > current_time:
                raise ValueError("Error: the start time boundary must "
                                 "precede the current time!")
            params['start'] = str(unix_start)
            params['end'] = str(unix_end)
        else:
            raise ValueError("Error: one of the time boundaries is None, "
                             "while the other is not!")
        json_data = self._httpclient.call_API(CITY_WEATHER_HISTORY_URL,
                                              params)
        return self._parsers['weather_history'].parse_JSON(json_data)