proposition: Lemma fgaddg0 : right_id fgzero fgadd.
proof: Proof. by move=> x; rewrite fgaddC fgadd0g. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap