struct
type t = Measurement_collection.t ref
let serialize t = serialize !t
let deserialize_exn t = ref (deserialize_exn t)
let create () = ref [Item.create `Creation]
let add collection log =
collection := log :: !collection
let clear c = c := [Item.create `Creation]
let concat cl : t =
List.concat_map cl ~f:(fun c -> !c) |> ref
let to_list c : Item.t list = !c
end