fact: Definition ff_flip_fixed_iff_inr (x : Cantor + Cantor + Cantor + Cantor) : (ff_flip x = x) <-> (is_inr x + is_inl_and is_inr x).
imports: HoTT.Basics HoTT.Types Idempotents HoTT.Truncations.Core Spaces.BAut Spaces.Cantor