> By default, the sorted function looks at the leftmost element of a tuple or other iterable, when sorting...

AFAIU, sorted() compares the whole object. 

>>> l = [(3, 2), (3, 1), (1, 1, 2), (1, 1)]

>>> sorted(l)

[(1, 1), (1, 1, 2), (3, 1), (3, 2)]

The way it reads, it seems like you're implying that sorted() does this:

>>> l = [(3, 2), (3, 1), (1, 1, 2), (1, 1)]

>>> sorted(l, key=lambda x: x[0])

[(1, 1, 2), (1, 1), (3, 2), (3, 1)]

> You'll find some excellent overview of the magic methods in this essay by Rafe Kettler: A Guide to Python's Magic Methods. He's mostly looking at Python 2.7, so does not pick up on the __next__ method, however you'll be able to fill in the blanks thanks to this course

This is unclear to me. What does the next() function do? How do I find the docs and source for it?

These are misspelled:

> comparitor

> compartor

These are great:

- http://www.scipy-lectures.org/intro/language/python_language.html

- http://nbviewer.jupyter.org/github/jrjohansson/scientific-python-lectures/blob/master/Lecture-1-Introduction-to-Python-Programming.ipynb

  - Something about sorted with a link to the docs would be a good addition.

IDK, I tend to find it much easier to just read the docs (and the source, if it's not clear).

sorted() is a built-in function (as indicated by the TypeError thrown by inspect.getfile(sorted)); which are in bltinmodule.c: