∀ {Γ : Type u_1} {Γ' : Type u_2} [inst : Inhabited Γ] [inst_1 : Inhabited Γ'] (a : Γ) (l : Turing.ListBlank Γ)
  (f : Γ → List Γ') (hf : ∃ n, f default = List.replicate n default),
  (Turing.ListBlank.cons a l).flatMap f hf = Turing.ListBlank.append (f a) (l.flatMap f hf)