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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 skewness(data):
 """ Returns the skewness of ``data``. """


    if len(data) == 0:
        return None

    num = moment(data, 3)
    denom = moment(data, 2) ** 1.5

    return num / denom if denom != 0 else 0.