try: import threading except ImportError: threading = None # use non-threaded behaviour
But then you'd have to sprinkle the rest of the code with "if threading is not None" tests. Brett's dummy_thread is an attempt to reduce this clutter.
the problem (if there is one) is that the proposed integration may break code that uses the above pattern.
I don't propose to automate this. I propose this: try: import threading except ImportError: import dummy_threading as threading
deadlocks doesn't always happen when you want them to, so it may not be obvious to developers and testers that their program isn't as reliable as it was before the upgrade.
So require testing on a system that has threads. --Guido van Rossum (home page: http://www.python.org/~guido/)