proposition: Lemma BZabs_positive b: intp b -> b <> \0z -> \0z <z (BZabs b).
proof: Proof. move => pa pb; apply /zlt0xP. apply /BZps_iP;split; first by apply BZabs_iN. by move => h; case: pb; apply:BZabs_0p. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)