Should upgrade to Python 3.x

[mmoser18]

Most pages don't work with Python 3.x (v3.7 in my case).
Reason is mostly that print is now a function and not a statement anymore, plus a few other subtle differences (standard functions that have been moved or removed etc.).
Not sure, whether it's possible to create a version that runs under both Python versions, but upgrading this tutorial such that it runs under the newer seems desirable.

[ricardoduarte]

Thank you for opening this issue. Actually, all of the examples included in this book version works only with Python 2.x (it is an old book).

There is a Python 3.x version of this book but it is only a printed version and it was written in Brazilian Portuguese.

When the editor rights expire, maybe we'll publish this book online.