docs: def enumerate_otus(fasta_filepath,
                     output_filepath=None,
                     label_prefix="",
                     label_suffix="",
                     retain_label_as_comment=False,
                     count_start=0):
      """ Writes unique, sequential count to OTUs
  
      fasta_filepath = input fasta filepath
      output_filepath = output fasta filepath
      label_prefix = string to place before enumeration
      label_suffix = string to place after enumeration
      retain_label_as_comment = if True, will place existing label in sequence
       comment, after a tab
      count_start = number to start enumerating OTUs with
  
      """
  
      fasta_i = open(fasta_filepath, "U")
  
      if not output_filepath:
          _, output_filepath = mkstemp(prefix='enumerated_seqs_',
                                       suffix='.fasta')
  
      fasta_o = open(output_filepath, "w")
  
      for label, seq in parse_fasta(fasta_i):
          curr_label = ">" + label_prefix + str(count_start) + label_suffix
          if retain_label_as_comment:
              curr_label += '\t' + label
          fasta_o.write(curr_label.strip() + '\n')
          fasta_o.write(seq.strip() + '\n')
          count_start += 1
  
      return output_filepath