struct   
  (** Call a command on a list of ~vcfs to produce a given ~final_vcf (hence the n-to-1 naming). *)
  let vcf_process_n_to_1_no_machine       ~host       ~vcftools       ~(run_program : Machine.Make_fun.t)       ?(more_edges = [])       ~vcfs       ~make_product       ~final_vcf       command_prefix     =     let open KEDSL in     let name = sprintf "%s-%s" command_prefix (Filename.basename final_vcf) in     let make =       run_program ~name         Program.(           Machine.Tool.(init vcftools)           && shf "%s %s > %s"             command_prefix             (String.concat ~sep:" "                (List.map vcfs ~f:(fun t -> Filename.quote t#product#path)))             final_vcf         ) in     workflow_node ~name       (make_product final_vcf)       ~make       ~edges:(         on_failure_activate           (Remove.path_on_host ~host final_vcf)         :: depends_on Machine.Tool.(ensure vcftools)         :: List.map ~f:depends_on vcfs         @ more_edges)   
  (** Concatenate VCF files.

We use this version where we don't yet have a Machine.t, as in "download_reference_genome.ml". *)

  let vcf_concat_no_machine       ~host       ~vcftools       ~(run_program : Machine.Make_fun.t)       ?more_edges       ~make_product       vcfs       ~final_vcf =     vcf_process_n_to_1_no_machine       ~make_product       ~host ~vcftools ~run_program ?more_edges ~vcfs ~final_vcf       "vcf-concat"   
  (** Sort a VCF file by choromosome position (it uses "vcf-sort" which itself relies on the "sort" unix tool having the "--version-sort" option).

We use this version where we don't yet have a Machine.t, as in "download_reference_genome.ml". *)

  let vcf_sort_no_machine       ~host       ~vcftools       ~(run_program : Machine.Make_fun.t)       ?more_edges       ~make_product       ~src ~dest () =     let run_program =       Machine.Make_fun.with_requirements run_program [`Memory `Big] in      vcf_process_n_to_1_no_machine       ~make_product       ~host ~vcftools ~run_program ?more_edges ~vcfs:[src] ~final_vcf:dest       "vcf-sort -c" end