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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def nac_v(msg):
 """Calculate NACv, Navigation Accuracy Category - Velocity Args: msg (string):
 28 bytes hexadecimal message string, TC = 19 Returns: int or string: 95% horizontal accuracy bounds for velocity, Horizontal Figure of Merit int or string: 95% vertical accuracy bounds for velocity, Vertical Figure of Merit """

    tc = typecode(msg)

    if tc != 19:
        raise RuntimeError("%s: Not an airborne velocity message, expecting TC = 19" % msg)

    msgbin = common.hex2bin(msg)
    NACv = common.bin2int(msgbin[42:45])

    try:
        HFOMr = uncertainty.NACv[NACv]['HFOMr']
        VFOMr = uncertainty.NACv[NACv]['VFOMr']
    except KeyError:
        HFOMr, VFOMr = uncertainty.NA, uncertainty.NA

    return HFOMr, VFOMr