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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 wind_bft(ms):
    "Convert wind from metres per second to Beaufort scale"
    if ms is None:
        return None
    for bft in range(len(_bft_threshold)):
        if ms < _bft_threshold[bft]:
            return bft
    return len(_bft_threshold)