docs: def sort_by_length_usearch61(seq_path,
                               output_dir=".",
                               minlen=64,
                               remove_usearch_logs=False,
                               HALT_EXEC=False,
                               output_fna_filepath=None,
                               log_name="length_sorted.log"):
      """ usearch61 application call to sort fasta file by length.
  
      seq_path:  fasta filepath to be clustered with usearch61
      output_dir: directory to output log, OTU mapping, and intermediate files
      minlen: minimum sequence length
      remove_usearch_logs: Saves usearch log files
      HALT_EXEC: application controller option to halt execution
      output_fna_filepath: path to write sorted fasta filepath
      log_name: filepath to write usearch61 generated log file
      """
  
      if not output_fna_filepath:
          _, output_fna_filepath = mkstemp(prefix='length_sorted', suffix='.fna')
  
      log_filepath = join(output_dir, log_name)
  
      params = {'--minseqlength': minlen,
                '--sortbylength': seq_path,
                '--output': output_fna_filepath
                }
      if not remove_usearch_logs:
          params['--log'] = log_filepath
  
      app = Usearch61(params, WorkingDir=output_dir, HALT_EXEC=HALT_EXEC)
  
      app_result = app()
  
      return output_fna_filepath, app_result