+type progress_cb = int -> int -> int64 -> int64 -> unit
+
+val set_progress_callback : t -> progress_cb -> unit
+(** [set_progress_callback g f] sets [f] as the progress callback function.
+ For some long-running functions, [f] will be called repeatedly
+ during the function with progress updates.
+
+ The callback is [f proc_nr serial position total]. See
+ the description of [guestfs_set_progress_callback] in guestfs(3)
+ for the meaning of these four numbers.
+
+ Note that if the closure captures a reference to the handle,
+ this reference will prevent the handle from being
+ automatically closed by the garbage collector. There are
+ three ways to avoid this: be careful not to capture the handle
+ in the closure, or use a weak reference, or call
+ {!Guestfs.clear_progress_callback} to remove the reference. *)
+
+val clear_progress_callback : t -> unit
+(** [clear_progress_callback g] removes any progress callback function
+ associated with the handle. See {!Guestfs.set_progress_callback}. *)
+