Module type Collection.Map.M
module type M =sig..end
type key 
type 'a t 
val is_empty : 'a t -> boolval mem : 'a t -> key -> boolval find : 'a t -> key -> 'aval size : 'a t -> intval iter : (key -> 'a -> unit) -> 'a t -> unitval fold : (key -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b