tcfail080.hs:27:1:
    Could not deduce (Collection c0 a)
      arising from the ambiguity check for `q'
    from the context (Collection c a)
      bound by the inferred type for `q': Collection c a => a -> Bool
      at tcfail080.hs:27:1-27
    The type variable `c0' is ambiguous
    When checking that `q'
      has the inferred type `forall (c :: * -> *) a.
                             Collection c a =>
                             a -> Bool'
    Probable cause: the inferred type is ambiguous