Goal:
  
  hd' : A.t
  tl'0 : list A.t
  hd : A.t
  tl : t
  tl' : t
  H : lt_ tl tl'
  IHlt_ : forall z : t, lt tl' z -> lt tl z
  H0 : A.lt hd hd'
  ============================
   (let H := CoreTactics.block in
    let H0 := CoreTactics.block in lt (hd :: tl) (hd' :: tl'0))


DEBUG:Going to execute:
match goal with
           | hyp:context [ CoreTactics.block ]
             |- _ =>
                 cbn beta in hyp; eqns_specialize_eqs_block hyp;
                  cbn[eq_rect_r eq_rect] in hyp
           end