Goal:
    A : Type  P : list A → list A → A → A → Type  Q : list A → A → Type
  ============================
   (All2_fold P [] [] × All_fold Q [] × All_fold Q [])


DEBUG:Going to execute:
fun tauto_flags X1 X2 id =>
             <coq-core.plugins.tauto::flatten_contravariant_conj@0>