simp[toFinArrowOpt, fintypeArrowEquivFinArrow]
ι : Type u_1
inst✝² : Fintype ι
inst✝¹ : DecidableEq ι
inst✝ : Encodable ι
α : Type u_2
f : ι → Option α
⊢ toFinArrowOpt f = none ↔ ∃ i, f i = none
ι : Type u_1
inst✝² : Fintype ι
inst✝¹ : DecidableEq ι
inst✝ : Encodable ι
α : Type u_2
f : ι → Option α
⊢ (∃ i, f (fintypeEquivFin.symm i) = none) ↔ ∃ i, f i = none