There are old, but still good and sometimes best, learning materials for all mainstream languages. That creates a challenge for learners, because learners shoul

There are old, but still good and sometimes best, learning materials for all mainstream languages. That creates a challenge for learners, because learners should be focusing on the future of the language, not its past. If you're learning C++ now, you really should be learning the C++1x style of writing it; if you're learning JavaScript, it should be ES6-style; and if you're learning Python, it should be Python 3. The older styles of these languages are still relevant to those who will need them for professional use on older code bases, but for a new user, they can be treated as more advanced material to be learned primarily for recognition but not for writing. Learn Python 3 now; add some Python 2 details later, if needed. And if you really love your Python 2 MOOC, go ahead and use it as an introduction. Almost everything they are showing you is both Python 2 AND Python 3, so you're learning Python 3. Then move on to intermediate-level material that is Python 3 and goes into a lot more detail, and you'll easily switch over.