Range.

    Formula:
    bb_range = u_bb - l_bb

def bb_range(data, period, std=2.0):
    """
    Range.

    Formula:
    bb_range = u_bb - l_bb
    """
    catch_errors.check_for_period_error(data, period)

    period = int(period)
    bb_range = (upper_bollinger_band(data, period, std) -
                lower_bollinger_band(data, period, std)
                )
    return bb_range