Discussion on: 3 Common Mistakes that Python Newbies Make

[rhymes]

A little detail on ordered dicts:

Technically dicts have been ordered since 3.6 on (C)Python, it's just that in 3.7 they decided that to be call "Python 3.7" any implementation has to have the insertion order.

So, dicts in Python 3.6+ are ordered only in the official version, which means that you might have portability issues if you depend on that behavior, but in 3.7+ you are garanteed they will be ordered, regardless of the implementation.

Difference with Python 2:

Python 2.7.15 (default, Jul  3 2018, 10:08:31)
[GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.2)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> a = {'b': 1, 'c': 3, 'a': '4'}
>>> a
{'a': '4', 'c': 3, 'b': 1}
>>>

Python 3.6.6 (default, Jul 20 2018, 18:34:07)
[GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.2)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> a = {'b': 1, 'c': 3, 'a': '4'}
>>> a
{'b': 1, 'c': 3, 'a': '4'}

[Thomas Landin]

Yep, that's what I meant by 3.7 being different on that point.