code: def export_freq_band(xfreq, bands, filename):
      heading_row_1 = ['Segment index',
                     'Start time',
                     'End time',
                     'Duration',
                     'Stitches',
                     'Stage',
                     'Cycle',
                     'Event type',
                     'Channel',
                     ]
      spacer = [''] * (len(heading_row_1) - 1)
      band_hdr = [str(b1) + '-' + str(b2) for b1, b2 in bands]
      xband = xfreq.copy()
      for seg in xband:
          bandlist = []
          for i, b in enumerate(bands):
              pwr, _ = band_power(seg['data'], b)
              bandlist.append(pwr)
          seg['band'] = bandlist
      as_matrix = asarray([
              [x['band'][y][chan] for y in range(len(x['band']))] \
              for x in xband for chan in x['band'][0].keys()])
      desc = get_descriptives(as_matrix)
      with open(filename, 'w', newline='') as f:
          lg.info('Writing to ' + str(filename))
          csv_file = writer(f)
          csv_file.writerow(['Wonambi v{}'.format(__version__)])
          csv_file.writerow(heading_row_1 + band_hdr)
          csv_file.writerow(['Mean'] + spacer + list(desc['mean']))
          csv_file.writerow(['SD'] + spacer + list(desc['sd']))
          csv_file.writerow(['Mean of ln'] + spacer + list(desc['mean_log']))
          csv_file.writerow(['SD of ln'] + spacer + list(desc['sd_log']))
          idx = 0
          for seg in xband:
              for chan in seg['band'][0].keys():
                  idx += 1
                  cyc = None
                  if seg['cycle'] is not None:
                      cyc = seg['cycle'][2]
                  data_row = list(
                          [seg['band'][x][chan] for x in range(
                                  len(seg['band']))])
                  csv_file.writerow([idx,
                                     seg['start'],
                                     seg['end'],
                                     seg['duration'],
                                     seg['n_stitch'],
                                     seg['stage'],
                                     cyc,
                                     seg['name'],
                                     chan,
                                     ] + data_row)