Goal:
    a : byte  b : byte  e : NoConfusion_byte a b
  ============================
   (noConfusion_byte_obligation_2 a b (noConfusion_byte_obligation_1 a b e) =
    e)


DEBUG:Going to execute:
match H with
           | H' => fail 2
           | _ => unify X Y; clear H' || clear H
           end