def band_width(high_data, low_data, period):
catch_errors.check_for_input_len_diff(high_data, low_data)<EOL>diff = np.array(high_data) - np.array(low_data)<EOL>bw = sma(diff, period)<EOL>return bw<EOL>
Bandwidth.

Formula:
BW = SMA(H - L)