fact: Definition not_impl2 := λ"t" λ"f" "f" @ (callcc @ "t") @ (callcc @ λ"g" "t" @ λ"a" "g") @ λ"c" "t" @ λ"a" λ"b" "c".
imports: ClassicalRealizability.Tactics ClassicalRealizability.BasicResults ClassicalRealizability.Subtyping