intro h
case mp
α : Type u_1
β : Type ?u.8604
xs✝ : List1.IndView α
ys : List1 α
x : α
xs : List1.IndView α
y : α
⊢ List1.cons x xs.toList1.toList = List1.cons y [] → IndView.pure y = IndView.cons x xs
case mp
α : Type u_1
β : Type ?u.8604
xs✝ : List1.IndView α
ys : List1 α
x : α
xs : List1.IndView α
y : α
h : List1.cons x xs.toList1.toList = List1.cons y []
⊢ IndView.pure y = IndView.cons x xs