fact: Definition natrP x : reflect (exists n, x = n%:R) (x \is a nat_num) := @ssrnum.Num.Theory.mc_2_0.natrP R x.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order ssralg poly ssrnum ssrint)