Goal:
  
  A : Type
  B : Type
  R : A → B → Prop
  R' : A → B → Prop
  x : A
  y : B
  l : list A
  l' : list B
  H : R x y
  H0 : Forall2 R l l'
  H2 : R' x y
  H3 : Forall2 R' l l'
  H1 : Forall2 (λ (x : A) (y : B), R x y ∧ R' x y) l l'
  ============================
   (R x y)


DEBUG:Going to execute:
match goal with
           | |- ?X1 → ?X2 => intro
           | |- ¬ _ => unfold not at 1; intro
           end