Goal:
  
  ============================
   (nth_error ?list_all 1 = Some false)


DEBUG:Going to execute:
let t := fresh in
           intro t; case t; clear t
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.