Python3?

According to the readme, it supports both python 2 and 3. But using python3 to run the first example (train) in the readme cause an error about xrange/range. So the question is how does it support python3? Using 2to3 is tested to be okay? TIA!

Start with the README's first `train` example and reproduce the reported Python 3 error involving `xrange` and `range`. Inspect the example's Python compatibility and the README's claim that Python 2 and 3 are supported; the work is complete when the supported Python 3 path is clear and the example no longer fails for this reason.

Written by the indexing model from the issue text.