The additional bit is that the Python bytecode itself can be stored as metadata on the PythonByteCode blocks. This will allow those classes to be removed entirely.

I think that the ideal API would be:

scfg = SCFG.from_python_function(python_func)

Or:

scfg = SCFG(python_func)

Also, this means, the ByteFlowRenderer can be removed too because PythonBytecodeBlocks will have the bytecode embedded and as such contain all the information they need to supply to be rendered.