fact: Definition hexagon_join_twist_sym A B C : trijoin_id_sym C A B o trijoin_twist A C B o trijoin_id_sym A B C == trijoin_twist B C A o trijoin_id_sym B A C o trijoin_twist A B C.
imports: Basics Types WildCat Join.Core Join.TriJoin Spaces.Nat.Core