* Verify that byte and Unicode strings are used consistently.
  Document how they are used.

* The ``FileUri`` class is ugly.
  Implement a nicer interface.

* Add an example for using streams.

* Improve the test suite.

* Track test coverage.

* Cython ≥ 0.23 provides the plugin ``Cython.Coverage``
  that can be added to ``.coveragerc``.
