Goal:
  
  A : Type
  P : A → A → Prop
  r : A
  r' : A
  H : Forall2 P [r] [r']
  H3 : P r r'
  H5 : Forall2 P [] []
  ============================
   (Forall2 P [] [] ∧ P r r')


DEBUG:Going to execute:
PTRDEBUGTACfun tac =>
             <Coq.Init.Tauto.with_uniform_flags>
              ltac:(fun flags => <Coq.Init.Tauto.intuition_gen> flags tac)