code: def addBarcodesToIdentifier(read, UMI, cell):
      '''extract the identifier from a read and append the UMI and
      cell barcode before the first space'''
  
      read_id = read.identifier.split(" ")
  
      if cell == "":
          read_id[0] = read_id[0] + "_" + UMI
      else:
          read_id[0] = read_id[0] + "_" + cell + "_" + UMI
  
      identifier = " ".join(read_id)
  
      return identifief addBarcodesToIdentifier(read, UMI, cell):
      '''extract the identifier from a read and append the UMI and
      cell barcode before the first space'''
  
      read_id = read.identifier.split(" ")
  
      if cell == "":
          read_id[0] = read_id[0] + "_" + UMI
      else:
          read_id[0] = read_id[0] + "_" + cell + "_" + UMI
  
      identifier = " ".join(read_id)
  
      return identifier
docs: extract the identifier from a read and append the UMI and
      cell barcode before the first space