code: def findbcode(cutters, longbar, read1):
      
      ## default barcode string
      for cutter in cutters[0]:
          ## If the cutter is unambiguous there will only be one.
          if not cutter:
              continue
          search = read1[1][:int(longbar[0]+len(cutter)+1)]
          barcode = search.rsplit(cutter, 1)
          if len(barcode) > 1:
              return barcode[0]
      ## No cutter found
      return barcode[0]
docs: find barcode sequence in the beginning of read