Default to Python 3 compatibility

[neirbowj]

Thank you for maintaining this great resource!

With Python 2 End of Life planned for about 19 months from now, it should be possible to run any snippet found on pysheets under the latest version of Python (3.6.5 today) unmodified. For example, all occurrences of print should be functions instead of statements. This is not to say that the snippets should not run under Python 2, but that the priority should be Python 3 compatibility.

[crazyguitar]

Ha! I total agree with you. I am still upgrading the snippets.

[neirbowj]

I'd be glad to help.

[crazyguitar]

That will be great. 👍