Set: pp::colors
  Set: pp::unicode
  Defined: f
  Defined: g
  Proved: T1
  Defined: h
  Proved: T2
theorem T2 (a b : Bool) : h a b ⇒ f b ⇒ a :=
    discharge (λ H : a ∨ b, discharge (λ H::1 : ¬ b, or::elim H (λ H : a, H) (λ H : b, absurd::elim a H H::1)))