Module CanonicalTest.Base__Tests

module C : module type of Base__.List
module L = Base__.List
val foo : L.t -> L.t
val bar : Base__.List.t -> Base__.List.t

This is just List.id, or rather L.id

val baz : Base__.List.t -> unit

Just seeing if Base__.List.t (Base__.List.t) gets rewriten to Base.List.t (Base.List.t)