fact: Definition ispullback_sigprod {D : Type} (P Q : D -> Type) : IsPullback (fun z:{d:D & P d * Q d} => 1%path : (z.1;fst z.2).1 = (z.1;snd z.2).1).
imports: HoTT.Basics HoTT.Types HFiber PathAny Cubical.PathSquare Diagrams.CommutativeSquares