code: def get_bar_data_from_undetermined(self, flowcells):
          
          bar_data = defaultdict(dict)
          # get undetermined barcodes for each lanes
          for lane_id, lane in flowcells.items():
              try:
                  for barcode, count in islice(lane['unknown_barcodes'].items(), 20):
                      bar_data[barcode][lane_id] = count
              except AttributeError:
                  pass
  
          # sort results
          bar_data = OrderedDict(sorted(
              bar_data.items(),
              key=lambda x: sum(x[1].values()),
              reverse=True
          ))
          return OrderedDict(
              (key, value) for key, value in islice(bar_data.items(), 20)
          )
docs: Get data to plot for undetermined barcodes.