If [fail] is passed, then failures cause this callback to
be called. If not, the global failure hook is called. *)
+val reopen : ?fail:exn callback -> Slave_types.inspection_data callback -> unit
+ (** [reopen cb] reruns the last {!open_domain} or {!open_images}
+ command, if there was one. *)
+
val run_command : ?fail:exn callback -> string -> unit callback -> unit
(** [run_command cmd] runs an external command [cmd]. This is
useful for possibly long-running commands as it keeps the