@staticmethod
def _calc_total_recording_time(epochlength_in_min, lights_on, lights_off):
    """
        returns the recording time in minutes, excluding lights on at begin and end
        :param epochlength_in_min:
        :param lights_on:
        :param lights_off:
        :return: RTR [min]
        """
    return (lights_on - lights_off) * epochlength_in_min
