fact: Definition norm_msets_ norm (l: mset T) := fold_map' (fun un => let '(u,n) := un in return_sum (norm u) n) (fun un l => let '(u,n) := un in add_to_sum (norm u) n l) l.
imports: Coq(Arith NArith List) Coq(FMapPositive Relations RelationClasses) AAC_tactics(Utils Constants)