Goal:
  
  A : Type
  i : nat
  IHi : ∀ l : list A,
          i < #|l| → nth_error l i = nth_error (List.rev l) (#|l| - S i)
  ============================
   (S i < 0 → None = None)


DEBUG:Going to execute:
<coq-core.plugins.ltac::auto@0> $1 $2 $3