fact: Definition prod_of_sigT {A B : Type} (p : {_ : A & B}) : A * B := let (a, b) := p in (a, b).
imports: QuickChick(QuickChick Generators) Lia mathcomp(ssreflect ssrnat ssrbool eqtype) QuickChick.RedBlack(redblack) List String Relations Wellfounded Lexicographic_Product