Make this Python2/Python3 compatible.
Make this Python2/Python3 compatible.

kpolimis/sklearn-forest-ci,scikit-learn-contrib/forest-confidence-interval,arokem/sklearn-forest-ci,uwescience/sklearn-forest-ci,scikit-learn-contrib/forest-confidence-interval,kpolimis/sklearn-forest-ci,arokem/sklearn-forest-ci,uwescience/sklearn-forest-ci