. simp [List.get]
case mk.zero
α : Type u_1
x y : α
xs : List α
vlt : Nat.zero < List.length xs + 2
⊢ List.get (x :: y :: xs) { val := Nat.zero, isLt := vlt } =
    List.get (y :: x :: xs) (shuffleIndex { val := Nat.zero, isLt := vlt })

case mk.succ
α : Type u_1
x y : α
xs : List α
n✝ : Nat
vlt : Nat.succ n✝ < List.length xs + 2
⊢ List.get (x :: y :: xs) { val := Nat.succ n✝, isLt := vlt } =
    List.get (y :: x :: xs) (shuffleIndex { val := Nat.succ n✝, isLt := vlt })
case mk.succ
α : Type u_1
x y : α
xs : List α
n✝ : Nat
vlt : Nat.succ n✝ < List.length xs + 2
⊢ List.get (x :: y :: xs) { val := Nat.succ n✝, isLt := vlt } =
    List.get (y :: x :: xs) (shuffleIndex { val := Nat.succ n✝, isLt := vlt })