proposition: Lemma pred_of_setK (A : finType) (s : {set A}) : [set x in s] = s.
proof: Proof. by apply/setP => i; rewrite inE. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix perm) ssr_ext ssralg_ext fdist