have : b = b' ∨ b ∈ bs := by simpa using h
case cons
β : Type u_1
inst✝ : Encodable β
b b' : β
bs : List β
ih : b ∈ bs → encode b < encode bs
h : b ∈ b' :: bs
⊢ encode b < encode (b' :: bs)
case cons
β : Type u_1
inst✝ : Encodable β
b b' : β
bs : List β
ih : b ∈ bs → encode b < encode bs
h : b ∈ b' :: bs
this : b = b' ∨ b ∈ bs
⊢ encode b < encode (b' :: bs)