"Python's Preprocessor", a really amazing blog post about abusing customs codecs to do arbitrary preprocessing steps on python files before the VM sees it: https://pydong.org/posts/PythonsPreprocessor/

Examples include: Python with braces, adding x++ etc to Python, but the best one is clearly running (very lightly prepared) C++ code with the python vm using the cppyy module (!) by running 'python test.cpp'