tcfail223.hs:10:10: error:
    Could not deduce (Class1 a)
      arising from the superclasses of an instance declaration
    from the context: Class3 a
      bound by the instance declaration at tcfail223.hs:10:10-29
    Possible fix:
      add (Class1 a) to the context of the instance declaration
    In the instance declaration for ‘Class2 a’