a.x : Nat b.x : Nat c.x : Nat b.y : Nat c.y : Nat c.z : Nat A.x a : Nat A.x (B.toA b) : Nat A.x (B.toA (C.toB c)) : Nat B.y b : Nat B.y (C.toB c) : Nat C.z c : Nat x.val : Nat y.val : Nat z.val : Nat d.x : Nat c.x : Nat x.val : Nat y.val : Nat (@Fin''.toFin0 5 z).val : Nat (@D.toA 5 d).x : Nat f.toFun 0 : Int