∀ {V : Type u_1} {G : SimpleGraph V} {u v u' v' : V} {p : G.Walk u v} (h : G.Adj u' v')
  (motive : (∃ i, ∃ (h_1 : i < p.darts.length), p.darts[i] = { fst := u', snd := v', adj := h }) → Prop)
  (x : ∃ i, ∃ (h_1 : i < p.darts.length), p.darts[i] = { fst := u', snd := v', adj := h }),
  (∀ (i : ℕ) (hi : i < p.darts.length) (h_1 : p.darts[i] = { fst := u', snd := v', adj := h }), motive ⋯) → motive x