val (+) : ('a, 'b) Base.Set.t -> ('a, 'b) Base.Set.t -> ('a, 'b) Base.Set.tval (-) : ('a, 'b) Base.Set.t -> ('a, 'b) Base.Set.t -> ('a, 'b) Base.Set.tval (&) : ('a, 'b) Base.Set.t -> ('a, 'b) Base.Set.t -> ('a, 'b) Base.Set.tval (-*) : ('a, 'b) Base.Set.t -> ('a, 'b) Base.Set.t -> ('a, 'b) Base.Set.t