def METHOD_NAME(self, ship):
    """
    The KML fragment that describes a trajectory as a <Placemark> tag
    The different coordinates are from the ship's positions, which
    of course need to have been sorted in chronological order first.
    """
    # the coordinates chunk
    coordinates = "\n".join([f"{position.longitude},{position.latitude},0"
                             for position in ship.positions])
    # that we put into a <Placemark>
    # notice that the Placemark refers to the style created for that ship
    template = Template("""