Make_stat.Bag_of_stats
val pack : unit -> Def.pack
val tree : unit -> Def.tree
val index : float list -> Def.index
val gc : unit -> Def.gc
val size_of_file : string -> int64
val disk : string -> Def.disk
val now : unit -> float
val create : string -> float list -> Def.pack Def.bag_of_stats_base