docs: def insert_taxon_in_new_fasta_file(self, aln):
          """primer4clades infers the codon usage table from the taxon names in the
          sequences.
  
          These names need to be enclosed by square brackets and be
          present in the description of the FASTA sequence. The position is not
          important. I will insert the names in the description in a new FASTA
          file.
  
          Returns:
              Filename of modified FASTA file that includes the name of the taxon.
          """
          new_seq_records = []
          for seq_record in SeqIO.parse(aln, 'fasta'):
              new_seq_record_id = "[{0}] {1}".format(self.taxon_for_codon_usage, seq_record.id)
              new_seq_record = SeqRecord(seq_record.seq, id=new_seq_record_id)
              new_seq_records.append(new_seq_record)
  
          base_filename = os.path.splitext(aln)
          new_filename = '{0}_modified{1}'.format(base_filename[0], base_filename[1])
          SeqIO.write(new_seq_records, new_filename, "fasta")
          return new_filename