fact: Definition join_sym_nat {A B A' B'} (f : A -> A') (g : B -> B') : join_sym A' B' o functor_join f g == functor_join g f o join_sym A B.
imports: Basics Types Cubical NullHomotopy Extensions Colimits.Pushout Truncations.Core Truncations.Connectedness Pointed.Core WildCat Spaces.Nat.Core