Goal:
  
  z : t
  hd : A.t
  tl : list A.t
  hd0 : A.t
  tl0 : list A.t
  hd' : A.t
  tl' : list A.t
  H : A.lt hd0 hd'
  ============================
   ({| pr1 := hd :: tl; pr2 := z |} =
    {| pr1 := hd0 :: tl0; pr2 := hd' :: tl' |} ->
    let H := CoreTactics.block in let H0 := CoreTactics.block in lt [] z)


DEBUG:Going to execute:
simplify * || simplify ?; cbv beta