fact: Definition qzt_truncate t := if t is QztHubNode (QztNode _ _ _ _ as t58) _ _ _ then t58 else t.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry color coloring quiz cfmap) fourcolor(cfquiz cfreducible)