Goal:
  
  ============================
   nat


DEBUG:Going to execute:
<coq-core.plugins.ltac::intro@1> $1

Goals:
  
  ============================
   nat

  
  ============================
   nat


DEBUG:Going to execute:
push_S_refine_num fin
Level 0: Backtrace:

No product even after head-reduction.
Level 0: Backtrace:

No product even after head-reduction.
Level 0: Backtrace:

No product even after head-reduction.
Level 1: Backtrace:

No product even after head-reduction.
Level 0: Backtrace:

No product even after head-reduction.

Goals:
  
  ============================
   nat

  
  ============================
   nat


DEBUG:Going to execute:
fun ev =>
             lazymatch ev with
             | S ?ev => refine (S _); push_S_refine_num ev
             | ?ev =>
                 let __ := open_constr:((eq_refl : ev = S _)) in
                 refine
                 0
             end

Goals:
  
  ============================
   nat

  
  ============================
   nat


DEBUG:Going to execute:
lazymatch ev with
           | S ?ev => refine (S _); push_S_refine_num ev
           | ?ev =>
               let __ := open_constr:((eq_refl : ev = S _)) in
               refine
               0
           end

Goals:
  
  ============================
   nat

  
  ============================
   nat


DEBUG:Going to execute:
ev