proposition: Lemma mmap_is_multiplicative : multiplicative (mmap f h).
proof: Proof. by apply/commr_mmap_is_multiplicative=> g m m'; apply/mulrC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap