Goal:
    A : Type  P : list A → A → Type  x : A  a : All_fold P [x]
  ============================
   (let H := CoreTactics.block in let H0 := CoreTactics.block in P [] x)


DEBUG:Going to execute:
needs_generalization id; DepElim.generalize_sig_dest id
Level 2: evaluation returns
(needs_generalization id; DepElim.generalize_sig_dest id) || idtac
where
id := a
of type
ident of type tacvalue

Level 1: evaluation returns
(needs_generalization id; DepElim.generalize_sig_dest id) || idtac
where
id := a
of type
ident of type tacvalue