unfold toNFA
α qs : Type
M : DFA α qs
⊢ (fun w => ∃ run, NFA.Run.last run ∈ M.F) = NFA.AcceptedLanguage (toNFA M)
α qs : Type
M : DFA α qs
⊢ (fun w => ∃ run, NFA.Run.last run ∈ M.F) =
    NFA.AcceptedLanguage { Z := M.Z, Q := M.Q, δ := Option.toFinset ∘ M.δ, Q₀ := {M.q₀}, F := M.F }