From the project page,
https://github.com/rjpower/falcon/
"... However, this doesn't mean that programs which use these constructs won't run. Any missing functionality is routed through the Python C API, foregoing any potential performance benefit you might have gotten from Falcon. So, though Falcon isn't a complete Python implementation, it should still run all of your code."
> Not yet! Lots of constructs (like catching exceptions, constructing objects, etc...) aren't implemented in the Falcon virtual machine.