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:
progress (autounfold with equations in e; simpl in e)
Level 1: evaluation returns
repeat progress (autounfold with equations in e; simpl in e)
where
e := a
of type
ident of type tacvalue