How to use the pyowm.utils.formatting.timeformat function in pyowm

def acquisition_time(self, timeformat='unix'):
        """Returns the UTC time telling when the image data was acquired by the satellite

        :param timeformat: the format for the time value. May be:
            '*unix*' (default) for UNIX time
            '*iso*' for ISO8601-formatted string in the format ``YYYY-MM-DD HH:MM:SS+00``
            '*date* for ``datetime.datetime`` object instance
        :type timeformat: str
        :returns: an int or a str

        """
        return formatting.timeformat(self._acquisition_time, timeformat)

def reference_time(self, timeformat='unix'):
        """
        Returns the GMT time telling when the SO2 samples have been measured

        :param timeformat: the format for the time value. May be:
            '*unix*' (default) for UNIX time
            '*iso*' for ISO8601-formatted string in the format ``YYYY-MM-DD HH:MM:SS+00``
            '*date* for ``datetime.datetime`` object instance
        :type timeformat: str
        :returns: an int or a str
        :raises: ValueError when negative values are provided

        """
        return formatting.timeformat(self.ref_time, timeformat)

def reference_time(self, timeformat='unix'):
        """
        Returns the GMT time telling when the CO samples have been measured

        :param timeformat: the format for the time value. May be:
            '*unix*' (default) for UNIX time
            '*iso*' for ISO8601-formatted string in the format ``YYYY-MM-DD HH:MM:SS+00``
            '*date* for ``datetime.datetime`` object instance
        :type timeformat: str
        :returns: an int or a str
        :raises: ValueError when negative values are provided

        """
        return formatting.timeformat(self.ref_time, timeformat)

def creation_time(self, timeformat='unix'):
        """Returns the UTC time of creation of this station

        :param timeformat: the format for the time value. May be:
            '*unix*' (default) for UNIX time, '*iso*' for ISO8601-formatted
            string in the format ``YYYY-MM-DD HH:MM:SS+00`` or `date` for
            a ``datetime.datetime`` object
        :type timeformat: str
        :returns: an int or a str or a ``datetime.datetime`` object or None
        :raises: ValueError

        """
        if self.created_at is None:
            return None
        return formatting.timeformat(self.created_at, timeformat)

boundary (defaults to ``None``, in which case the current datetime
            will be used)
        :type end: int, ``datetime.datetime`` or ISO8601-formatted string
        :return: a list of *UVIndex* instances or empty list if data is not available
        :raises: *ParseResponseException* when OWM UV Index API responses' data
            cannot be parsed, *APICallException* when OWM UV Index API can not be
            reached, *ValueError* for wrong input values
        """
        geo.assert_is_lon(lon)
        geo.assert_is_lat(lat)
        assert start is not None
        start = formatting.timeformat(start, 'unix')
        if end is None:
            end = timestamps.now(timeformat='unix')
        else:
            end = formatting.timeformat(end, 'unix')
        params = {'lon': lon, 'lat': lat, 'start': start, 'end': end}
        json_data = self.uv_client.get_uvi_history(params)
        uvindex_list = [uvindex.UVIndex.from_dict(item) for item in json_data]
        return uvindex_list

raise ValueError("'alt' value must not be negative")
        self.id = id
        self.created_at = created_at
        if self.created_at is not None:
            padded_created_at = self._format_micros(created_at)
            t = dt.strptime(padded_created_at,
                            '%Y-%m-%dT%H:%M:%S.%fZ').replace(
                                tzinfo=formatting.UTC())
            self.created_at = formatting.timeformat(t, 'unix')
        self.updated_at = updated_at
        if self.updated_at is not None:
            padded_updated_at = self._format_micros(updated_at)
            t = dt.strptime(padded_updated_at,
                            '%Y-%m-%dT%H:%M:%S.%fZ').replace(
                                tzinfo=formatting.UTC())
            self.updated_at = formatting.timeformat(t, 'unix')
        self.external_id = external_id
        self.name = name
        self.lon = lon
        self.lat = lat
        self.alt = alt
        self.rank = rank

def reception_time(self, timeformat='unix'):
        """
        Returns the GMT time telling when the NO2 observation has been received
        from the OWM Weather API

        :param timeformat: the format for the time value. May be:
            '*unix*' (default) for UNIX time
            '*iso*' for ISO8601-formatted string in the format ``YYYY-MM-DD HH:MM:SS+00``
            '*date* for ``datetime.datetime`` object instance
        :type timeformat: str
        :returns: an int or a str
        :raises: ValueError when negative values are provided

        """
        return formatting.timeformat(self.rec_time, timeformat)

def creation_time(self, timeformat='unix'):
        """Returns the UTC time of creation of this aggregated measurement

        :param timeformat: the format for the time value. May be:
            '*unix*' (default) for UNIX time, '*iso*' for ISO8601-formatted
            string in the format ``YYYY-MM-DD HH:MM:SS+00`` or `date` for
            a ``datetime.datetime`` object
        :type timeformat: str
        :returns: an int or a str or a ``datetime.datetime`` object or None
        :raises: ValueError

        """
        if self.created_at is None:
            return None
        return formatting.timeformat(self.created_at, timeformat)

def reference_time(self, timeformat='unix'):
        """
        Returns the GMT time telling when the NO2 samples have been measured

        :param timeformat: the format for the time value. May be:
            '*unix*' (default) for UNIX time
            '*iso*' for ISO8601-formatted string in the format ``YYYY-MM-DD HH:MM:SS+00``
            '*date* for ``datetime.datetime`` object instance
        :type timeformat: str
        :returns: an int or a str
        :raises: ValueError when negative values are provided

        """
        return formatting.timeformat(self.ref_time, timeformat)

def creation_time(self, timeformat='unix'):
        """Returns the UTC time of creation of this aggregated measurement

        :param timeformat: the format for the time value. May be:
            '*unix*' (default) for UNIX time, '*iso*' for ISO8601-formatted
            string in the format ``YYYY-MM-DD HH:MM:SS+00`` or `date` for
            a ``datetime.datetime`` object
        :type timeformat: str
        :returns: an int or a str or a ``datetime.datetime`` object or None
        :raises: ValueError

        """
        if self.timestamp is None:
            return None
        return formatting.timeformat(self.timestamp, timeformat)