Goal:
  
  A : Type
  P : list A → Type
  h1 : P []
  h2 : ∀ (a : A) (l : list A), P l → P (l ++ [a])
  l : list A
  ============================
   (∀ l : list A, P (rev l))


DEBUG:Going to execute:
<coq-core.plugins.ltac::clear@0> $1
DEBUG LTAC Evaluated term: rev_invol
DEBUG LTAC Evaluated term: rev_invol
DEBUG LTAC Evaluated term: (rev l)