code: def _apply_identical_sequences_prefilter(self,
                                               seq_path):
          
          # creating mapping for de-replicated reads
          seqs_to_cluster, exact_match_id_map =\
              self._prefilter_exact_matches(parse_fasta(seq_path))
  
          # create temporary file for storing the de-replicated reads
          fd, unique_seqs_fp = mkstemp(
              prefix='SwarmExactMatchFilter', suffix='.fasta')
          close(fd)
  
          self.files_to_remove.append(unique_seqs_fp)
  
          # write de-replicated reads to file
          unique_seqs_f = open(unique_seqs_fp, 'w')
          for seq_id, seq in seqs_to_cluster:
              unique_seqs_f.write('>%s_%d\n%s\n'
                                  % (seq_id,
                                     len(exact_match_id_map[seq_id]),
                                     seq))
          unique_seqs_f.close()
  
          return exact_match_id_map, unique_seqs_fp
docs: Input : seq_path, a filepath to input FASTA reads
              Method: prepares and writes de-replicated reads
                      to a temporary FASTA file, calls
                      parent method to do the actual
                      de-replication
              Return: exact_match_id_map, a dictionary storing
                      de-replicated amplicon ID as key and
                      all original FASTA IDs with identical
                      sequences as values;
                      unique_seqs_fp, filepath to FASTA file
                      holding only de-replicated sequences