Review of Python usage

All the Python here (apart from the test suite itself) was unnecessary to see a passing test suite; the class in `my_code.py` was probably put there to document the reflected C++ class, but should have used docstrings (see 08850e3) to do so. It wasn't needed at all to sanely execute the C++ code from Python.

The test suite itself should have probably covered a few more interesting cases and documented them more fully; there is a single test case for the `cluster` method and it's not clear why the parameters that were chosen were chosen.

Further comments in the diff.