Python 2 or 3?
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There are (still) two versions of Python in the wild: Python 2 and Python 3. Now, as **Python 2 has finally reached end of life** (as of 01.01.2020), the answer is crystal clear: **use Python 3**.


.. note::

    This section is here for rather historic reasons. Python 2 shall *not* be used any further for new projects, and all existing projects using this version should definitely be ported to Python 3. However, part of the reality (not only) in science is the habit of "never change a running system", therefore you might still get in touch with old Python 2 code.


Python 2 end of life
====================

Those interested in the whereabouts of Python 2 end of life (EOL) may find the following information useful:

* `PEP 373 -- Python 2.7 Release Schedule <https://www.python.org/dev/peps/pep-0373/>`_

* `Sunsetting Python 2 <https://www.python.org/doc/sunset-python-2/>`_

* `Sunsetting Python 2 support <https://python3statement.org/>`_


But I have old Python 2 code
============================

Spend all your available time porting this code to Python 3 as soon as possible, making use of such tools as `2to3 <https://docs.python.org/3.8/library/2to3.html>`_.

If that's not possible, *e.g.* due to legacy code from a vendor, wrap it and minimise the interaction with the old code to a *single* place in your project if ever possible.