conv =>
  lhs
  congr
  lhs
  intro x
  rw [bind_inr]
F : Type u → Type u
inst : QPF F
R S : Type u
x : R
k : R → Free F S
⊢ construct ((fun x => corec (bind.automaton k) (Sum.inr x)) <$> destruct (k x)) = k x
F : Type u → Type u
inst : QPF F
R S : Type u
x : R
k : R → Free F S
⊢ construct ((fun x => x) <$> destruct (k x)) = k x