code: def band_width(high_data, low_data, period):
      
      catch_errors.check_for_input_len_diff(high_data, low_data)
      diff = np.array(high_data) - np.array(low_data)
      bw = sma(diff, period)
      return bw
docs: Bandwidth.
  
      Formula:
      BW = SMA(H - L)