Goal:
  
  A : Type
  B : Type
  C : Type
  D : Type
  E : Type
  P : E → A → Type
  Q : C → A → Type
  R : B → D → Type
  f : B → C → E
  b : B
  l : list B
  l''' : list D
  hb : All2 R (b :: l) l'''
  x : C
  y : A
  l0 : list C
  l' : list A
  r : Q x y
  ha : All2 Q l0 l'
  hlen : #|b :: l| = #|x :: l0|
  ============================
   ((∀ (x : B) (y : C) (z : A) (w : D), R x w → Q y z → P (f x y) z)
    → (∀ (l : list B) (l''' : list D),
         All2 R l l''' → #|l| = #|l0| → All2 P (map2 f l l0) l')
      → let H := CoreTactics.block in
        All2 P (map2 f (b :: l) (x :: l0)) (y :: l'))


DEBUG:Going to execute:
CoreTactics.block_goal
Level 14: evaluation returns
idtac of type tacvalue

Level 12: evaluation returns
idtac of type tacvalue

Level 11: evaluation returns
idtac of type tacvalue

Level 9: evaluation returns
idtac of type tacvalue

Level 7: evaluation returns
idtac of type tacvalue

Level 6: evaluation returns
idtac of type tacvalue

Level 4: evaluation returns
idtac of type tacvalue

Level 2: evaluation returns
idtac of type tacvalue

Level 1: evaluation returns
idtac of type tacvalue