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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 average_true_range(close_data, period):
 """ Average True Range. Formula: ATRt = ATRt-1 * (n - 1) + TRt / n """

    tr = true_range(close_data, period)
    atr = smoothed_moving_average(tr, period)
    atr[0:period-1] = tr[0:period-1]
    return atr