Make3_using_map2_local.X
type ('a, 'd, 'e) t
val return : 'a -> ('a, _, _) t
val map2 : ('a, 'd, 'e) t -> ('b, 'd, 'e) t -> f:('a -> 'b -> 'c) -> ('c, 'd, 'e) t
val map : [ `Define_using_map2 | `Custom of ('a, 'd, 'e) t -> f:('a -> 'b) -> ('b, 'd, 'e) t ]