module Useful:sig
..end
val bool_of_opt : 'a option -> bool
module StrMap:Map.S
with type key = string
module StrSet:Set.S
with type elt = string
module IntMap:Map.S
with type key = int
module IntSet:Set.S
with type elt = int
type'a
fprintf =Format.formatter -> 'a -> unit
module type ORD_PRT =sig
..end