fact: Fixpoint ntree_to_ltree {A : Type} (t : ntree A) {struct t} : ltree A := match t with nnode _ x f => lnode A x (nforest_to_list_ltree A f) end with nforest_to_list_ltree (A : Type) (f : nforest A) {struct f} : list (ltree A) := match f with nnil _ => nil | ncons _ t f' => ntree_to_ltree t :: nforest_to_list_ltree A f' end.
imports: List