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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 middle_bollinger_band(data, period, std=2.0):
 """ Middle Bollinger Band. Formula: m_bb = sma() """

    catch_errors.check_for_period_error(data, period)

    period = int(period)
    mid_bb = sma(data, period)

    return mid_bb