intro x y h₁
F : Type u → Type u
inst : QPF F
R S : Type u
k : R → Free F S
⊢ ∀ (x y : QPF.M (FreeF F S)),
    corec (bind.automaton k) (Sum.inr x) = y →
      QPF.M.liftr (FreeF F S) (fun x y => corec (bind.automaton k) (Sum.inr x) = y) (QPF.M.destruct x)
        (QPF.M.destruct y)
F : Type u → Type u
inst : QPF F
R S : Type u
k : R → Free F S
x y : QPF.M (FreeF F S)
h₁ : corec (bind.automaton k) (Sum.inr x) = y
⊢ QPF.M.liftr (FreeF F S) (fun x y => corec (bind.automaton k) (Sum.inr x) = y) (QPF.M.destruct x) (QPF.M.destruct y)