def METHOD_NAME(floating_positions,
                       beached_positions,
                       start_time,
                       end_time,
                       uncertain):
    data = {'certain': "Uncertainty" if uncertain else "Best Guess",
            'start_time': start_time,
            'end_time': end_time,
            'date_string': start_time}
    kml = []
    kml.append(timestep_header_template.format(**data))
    for status, positions in [('Floating', floating_positions),
                              ('Beached', beached_positions)]:
        color = "Red" if uncertain else "Yellow"
        if status == "Floating":
            data['style'] = "#" + color + "DotIcon"
        else:
            data['style'] = "#" + color + "XIcon"
        data['status'] = status
        kml.append(one_run_header.format(**data))
        for point in positions:
            kml.append(point_template.format(*point[:2]))
        kml.append(one_run_footer)
    kml.append(timestep_footer)
    return "".join(kml)