proposition: Lemma size_flipq q :size (flatq (flipq q)) = size (flatq q).
proof: Proof. elim: q => //= *; rewrite ?size_cat 1?addnC; congr _.+1; auto. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry coloring)