proposition: Lemma finsupp_msetn n a : finsupp (msetn n a) = if n > 0 then [fset a] else fset0.
proof: Proof. by apply/fsetP => i; rewrite !inE; case: ifP => //=; rewrite inE. Qed.
imports: mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop tuple) finmap