Goal:
  
  a : A.t
  x : list A.t
  IHx : forall y : t, CompareSpec (x = y) (lt x y) (lt y x) (compare x y)
  t0 : A.t
  y : list A.t
  H : A.lt a t0
  ============================
   (CompareSpec (a :: x = t0 :: y) (lt (a :: x) (t0 :: y))
      (lt (t0 :: y) (a :: x)) Lt)


DEBUG:Going to execute:
repeat constructor