Updates research/python

research/python.md

@@ -2,6 +2,30 @@
 
 ## Learning Python
 
+### Which version to start? 2.x or 3.x?
+
+Short answer: start learning 3.x and, if needed, check the differences with 2.x.
+
+From [Should I use Python 2 or Python 3 for my development activity?](Should I use Python 2 or Python 3 for my development activity?):
+
+    Besides, several aspects of the core language (such as print and exec being
+    statements, integers using floor division) have been adjusted to be easier for
+    newcomers to learn and to be more consistent with the rest of the language, and
+    old cruft has been removed (for example, all classes are now new-style,
+    "range()" returns a memory efficient iterable, not a list as in 2.x).
+
+    [...]
+
+    In particular, instructors introducing Python to new programmers should
+    consider teaching Python 3 first and then introducing the differences in Python
+    2 afterwards (if necessary), since Python 3 eliminates many quirks that can
+    unnecessarily trip up beginning programmers trying to learn Python 2.
+
+Also:
+
+* [Python Future: Easy, clean, reliable Python 2/3 compatibility](http://python-future.org/).
+* [Should I learn Python 2 or 3?](https://www.dataquest.io/blog/python-2-or-3/).
+
 ### General
 
 * Everything is an object. Really? What about symbols like + - and =?
@@ -73,6 +97,10 @@ Python encourages polymorphism:
 So remember that when [copying](https://stackoverflow.com/questions/2612802/how-to-clone-or-copy-a-list#2612815)
 or referencing a list.
 
+### Nice stuff
+
+* [Verbose Regular Expressions](http://www.diveintopython3.net/regular-expressions.html#verbosere).
+
 ## Implementations
 
 * [MicroPython - Python for microcontrollers](http://micropython.org/) ([compiling](https://github.com/micropython/micropython/wiki/Getting-Started).