Turbulence.

    Args:
        msg (String): 28 bytes hexadecimal message string

    Returns:
        int: Turbulence level. 0=NIL, 1=Light, 2=Moderate, 3=Severe

def turb45(msg):
    """Turbulence.

    Args:
        msg (String): 28 bytes hexadecimal message string

    Returns:
        int: Turbulence level. 0=NIL, 1=Light, 2=Moderate, 3=Severe

    """
    d = hex2bin(data(msg))
    if d[0] == '0':
        return None

    turb = bin2int(d[1:3])
    return turb