let wget       ~host ~(run_program : Machine.Make_fun.t)       url destination =     let open KEDSL in     let name = "wget-" ^ Filename.basename destination in     workflow_node       (single_file destination ~host) ~name       ~make:(         run_program ~name           ~requirements:(Machine.Make_fun.downloading [])           Program.(             exec ["mkdir"; "-p"; Filename.dirname destination]             && shf "wget %s -O %s"               (Filename.quote url) (Filename.quote destination)))       ~edges:[         on_failure_activate (Remove.path_on_host ~host destination);       ]