Goal:
  
  A : Type
  P : A → Prop
  a : A
  l : list A
  l' : list A
  IHl : Forall P (l ++ l') → Forall P l ∧ Forall P l'
  H0 : P a
  H1 : Forall P (l ++ l')
  ============================
   (Forall P (a :: l))


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

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.
Level 1: Backtrace:

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.