unfold Add.add
x y : Int
⊢ { hAdd := fun a b => Add.add a b }.1 x y = { hAdd := fun a b => Add.add a b }.1 y x
x y : Int
⊢ { hAdd := fun a b => instAddInt.1 a b }.1 x y = { hAdd := fun a b => instAddInt.1 a b }.1 y x