Goal:
  
  A : Type
  x : A
  xs : list A
  f : A → bool
  H0 : ∀ f0 : A → bool,
         (λ (x : A) (_ : In x xs), f x) = (λ (x : A) (_ : In x xs), f0 x)
         → forallb_InP xs (λ (x : A) (_ : In x xs), f x) = forallb f0 xs
  ============================
   (forallb_InP (x :: xs) (λ (x0 : A) (_ : In x0 (x :: xs)), f x0) =
    forallb f (x :: xs))


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<coq-core.plugins.ltac::discriminate@0>
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