Execution model > Naming and binding > global:

appendExecution model > Naming and binding > global:
https://docs.python.org/3.6/reference/executionmodel.html

It would be impossible to assign to a global variable without global, although free variables may refer to globals without being declared global.
https://docs.python.org/3.6/reference/simple_stmts.html#the-global-statement

IDLE

Raymond Hettinger, “Being a Core Developer in Python”
PyBay2016
SF Python

21:45 IDLE is not the world’s greatest editor. It crashes. It has performance problems.
… Go get yourself a real editor!

42:45 A general purpose programming language can do anything.
We don’t know in advance what problem we’re solving.
Because of that, it’s very easy to invent problems…

46:30 don’t be a hypergeneralizer

list.sort(key=len) sorted(iterable, key=str.lower)

Documentation » Python HOWTOs » Sorting HOW TO
https://docs.python.org/3/howto/sorting.html

l4 = sorted(l4, key=lambda concept: (concept[0].lower(), concept[1])
http://stackoverflow.com/questions/10269701/case-insensitive-list-sorting-without-lowercasing-the-result

https://developers.google.com/edu/python/sorting

http://stackoverflow.com/questions/4659524/how-to-sort-by-length-of-string-followed-by-alphabetical-order