For trivial programs sure... not when dealing with encoders, decoders, binary formats, etc, etc. It all depends on how they wrote their Python 2.7 code. You c

For trivial programs sure... not when dealing with encoders, decoders, binary formats, etc, etc. It all depends on how they wrote their Python 2.7 code. You can write it oblivious to Python 3 and screw things up, or you can write it in a way that you know you'll eventually support Python 3. In the latter case, you might as well just support both right away though.