module type S3 = sig .. end
sig
end
type ('a, 'b, 'c) t
('a, 'b, 'c)
val equal : 'a Equal.equal -> 'b Equal.equal -> 'c Equal.equal -> ('a, 'b, 'c) t Equal.equal
'a Equal.equal -> 'b Equal.equal -> 'c Equal.equal -> ('a, 'b, 'c) t Equal.equal