fact: Definition ispullback_isequiv_functor_hfiber {A B C D : Type} {f : A -> B} {g : C -> D} {h : A -> C} {k : B -> D} (p : k o f == g o h) (e : forall b:B, IsEquiv (functor_hfiber p b)) : IsPullback p.
imports: HoTT.Basics HoTT.Types HFiber PathAny Cubical.PathSquare Diagrams.CommutativeSquares