How to use the gpxpy.gpx function in gpxpy

Point -> add as a Way Point
        LineString -> add all Points in a Route
        Collection (of LineString or Point) -> add as a route, concatening all points
        """
        if isinstance(geom, GeometryCollection):
            for i, g in enumerate(geom):
                self.geomToGPX(g, u"%s (%s)" % (name, i), description)
        elif isinstance(geom, Point):
            wp = self._point_to_GPX(geom)
            wp.name = name
            wp.description = description
            self.gpx.waypoints.append(wp)
        elif isinstance(geom, LineString):
            gpx_route = gpxpy.gpx.GPXRoute(name=name, description=description)
            gpx_route.points = [self._point_to_GPX(point, klass=gpxpy.gpx.GPXRoutePoint) for point in geom]
            self.gpx.routes.append(gpx_route)
        else:
            raise ValueError("Unsupported geometry %s" % geom)

def extract_segment_from_gpx_file(content, segment_id):
    gpx_content = gpxpy.parse(content)
    if len(gpx_content.tracks) == 0:
        return None

    track_segment = get_gpx_segments(
        gpx_content.tracks[0].segments, segment_id
    )

    gpx = gpxpy.gpx.GPX()
    gpx_track = gpxpy.gpx.GPXTrack()
    gpx.tracks.append(gpx_track)
    gpx_segment = gpxpy.gpx.GPXTrackSegment()
    gpx_track.segments.append(gpx_segment)

    for point_idx, point in enumerate(track_segment[0].points):
        gpx_segment.points.append(
            gpxpy.gpx.GPXTrackPoint(
                point.latitude, point.longitude, elevation=point.elevation
            )
        )

    return gpx.to_xml()

def gpx_export(move):

    gpx = gpxpy.gpx.GPX()
    gpx.creator = "OpenMoves - http://www.openmoves.net/"

    # Create first track in our GPX:
    gpx_track = gpxpy.gpx.GPXTrack()
    gpx.tracks.append(gpx_track)

    # Create first segment in our GPX track:
    gpx_segment = gpxpy.gpx.GPXTrackSegment()
    gpx_track.segments.append(gpx_segment)

    # Create points:
    gps_samples = move.samples.filter(Sample.sample_type.like('gps-%')).order_by(Sample.time.asc())

    if gps_samples.count() == 0:
        flash("No GPS samples found for GPX export", 'error')
        return None

    for gps_sample in gps_samples:
        gpx_segment.points.append(gpxpy.gpx.GPXTrackPoint(latitude=radian_to_degree(gps_sample.latitude),
                                                          longitude=radian_to_degree(gps_sample.longitude),
                                                          elevation=gps_sample.gps_altitude,
                                                          time=move.date_time + gps_sample.time,
                                                          position_dilution=gps_sample.gps_hdop))