fact: Definition flipqz qz := if qz is Quiz (QaskR qa0 q01) (QaskR qa1 q10) then Quiz (QaskR qa0 (flipq q10)) (QaskR qa1 (flipq q01)) else qz.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry coloring)