Goal:
  
  A : Type
  H : ReflectEq A
  a1 : A
  l1 : list A
  a2 : A
  l2 : list A
  prefix : list A
  l1' : list A
  l2' : list A
  ============================
   (split_prefix l1 l2 = (prefix, l1', l2')
    → (∀ (H := CoreTactics.block) (l3 l4 l : list A),
         {| pr1 := l1; pr2 := l2 |} = {| pr1 := l3; pr2 := l4 |}
         → split_prefix l1 l2 = split_prefix l3 l4
           → let H0 := CoreTactics.block in
             is_prefix l l3
             → is_prefix l l4 → is_prefix l (fst (fst (split_prefix l3 l4))))
      → (a1 == a2) = true
        → ∀ (H := CoreTactics.block) (l3 l4 l : list A),
            {| pr1 := a1 :: l1; pr2 := a2 :: l2 |} =
            {| pr1 := l3; pr2 := l4 |}
            → (a1 :: prefix, l1', l2') = split_prefix l3 l4
              → let H0 := CoreTactics.block in
                is_prefix l l3
                → is_prefix l l4
                  → is_prefix l (fst (fst (split_prefix l3 l4))))


DEBUG:Going to execute:
intro || (let H := fresh in
                     intro
                     H)
DEBUG LTAC Evaluated term: ((∀ (H := CoreTactics.block) (l3 l4 l : list A),
                               {| pr1 := l1; pr2 := l2 |} =
                               {| pr1 := l3; pr2 := l4 |}
                               → split_prefix l1 l2 = split_prefix l3 l4
                                 → let H0 := CoreTactics.block in
                                   is_prefix l l3
                                   → is_prefix l l4
                                     → is_prefix l
                                         (fst (fst (split_prefix l3 l4))))
                            → (a1 == a2) = true
                              → ∀ (H := CoreTactics.block) (l3 l4 l : list A),
                                  {| pr1 := a1 :: l1; pr2 := a2 :: l2 |} =
                                  {| pr1 := l3; pr2 := l4 |}
                                  → (a1 :: prefix, l1', l2') =
                                    split_prefix l3 l4
                                    → let H0 := CoreTactics.block in
                                      is_prefix l l3
                                      → is_prefix l l4
                                        → is_prefix l
                                            (fst (fst (split_prefix l3 l4))))
DEBUG LTAC Evaluated term: Prop