def metronixName(ext: str, sensor: str, serial: int, chopper: bool) ->str:
    """Get Metronix calibration file name
    
    Parameters
    ----------
    ext : str
        Calibration file extension
    sensor : str
        Sensor name
    serial : int
        The sensor serial number
    chopper : bool
        Boolean flag for chopper on or off

    Returns
    -------
    out : str
        Name of calibration file
    """
    if sensor == '' and not serial > 0:
        return None
    return '{}{}.{}'.format(sensor, serial, ext)
