Goal:
    hd : A.t  tl : list A.t  x : t
  ============================
   ({| pr1 := x; pr2 := x |} = {| pr1 := []; pr2 := hd :: tl |} ->
    let H := CoreTactics.block in let H0 := CoreTactics.block in False)


DEBUG:Going to execute:
simplify * || simplify ?