Goal:
  
  A : Type
  P : nat → A → Type
  f : nat → A → A
  n : nat
  H : ∀ (n : nat) (x : A), P n x → f n x = x
  ============================
   ([] = [])


DEBUG:Going to execute:
F x2 x1 x0
Level 0: Backtrace:

P is used in hypothesis H.
Level 0: Backtrace:

P is used in hypothesis H.
Level 0: Backtrace:

P is used in hypothesis H.
Level 0: Backtrace:

P is used in hypothesis H.
Level 0: Backtrace:

P is used in hypothesis H.
Level 1: Backtrace:

P is used in hypothesis H.
Level 0: Backtrace:

P is used in hypothesis H.