def METHOD_NAME(self, modifier=1.0, timestep=None):
    """
    sawtooth 0->1, looping every 65.536/modifier seconds
    lower modifier, slower looping
    you can consider modifier = 1 / sawtooth period
    """
    period = self._conversion_factor / modifier
    if timestep is None:
        timestep = self._dt
    return (timestep % period) / period