Goal:
    z : t  hd : A.t  tl : list A.t  H : lt (hd :: tl) z
  ============================
   (lt [] z)


DEBUG:Going to execute:
try intros until H; intro_block_id H || intro_block H
Level 1: evaluation returns
try intros until H; intro_block_id H || intro_block H;
 (try simpl in H; DepElim.simplify_equations_in H)
where
H := H
of type
ident of type tacvalue