fact: Definition sew_dart_at i : finType := match i with | SewDisk => Gd | SewRest => [the finType of {xr | xr \notin bGr}] end.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry color patch)