Goal:
  
  A : Type
  P : list A → A → Type
  d : A
  Γ : list A
  a : All_fold P Γ
  p : P Γ d
  b : All_fold P Γ
  p0 : P Γ d
  ============================
   (All_fold_cons P a p = All_fold_cons P a p)


DEBUG:Going to execute:
constructor