fact: Definition V_cart_prod (a : V) (b : V) : V := set (fun x : [a] * [b] => [func_of_members (fst x), func_of_members (snd x)]).
imports: HoTT.Basics HoTT.Types HSet TruncType Colimits.SpanPushout HoTT.Truncations.Core Colimits.Quotient