proposition: Lemma Creal_Im x : 'Im x \is real.
proof: Proof. rewrite ImE CrealE fmorph_div rmorph_nat rmorphM /= rmorphB conjCK. by rewrite conjCi -opprB mulrNN. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)