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more discussion and whatnot
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‎README.md‎

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# Playful Python
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---
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title: "Playful Python: Learning the language through games and puzzles"
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author: Ken Youens-Clark
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...
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# Introduction
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> "The only way to learn a new programming language is by writing programs in it." - Dennis Ritchie
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## Author
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Ken Youens-Clark is a Sr. Scientific Programmer in the lab of Dr. Bonnie Hurwitz at the University of Arizona. He started college as a music major at the University of North Texas but changed to English lit for his BA in 1995. He started programming at his first job out of college, working through several languages and companies before landing in bioinformatics in 2001. In 2019 he earned his MS in Biosystems Engineering, and enjoys helping people learn programming. When he's not working, he likes playing music, riding bikes, cooking, and being with his wife and children.
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## Copyright
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© Ken Youens-Clark 2019

‎article/Makefile‎

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.PHONY: pdf test
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pdf:
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pandoc README.md -o README.pdf
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.PHONY: test
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test:
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pytest -v test.py
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pytest -xv test.py

‎article/README.md‎

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Write a Python program called `article.py` that will select `a` or `an` for a given word depending on whether the word starts with a consonant or vowel, respectively.
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When run with no arguments or the `-h|--help` flags, it should print a usage statement:
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````
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$ ./article.py
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usage: article.py [-h] str
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optional arguments:
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-h, --help show this help message and exit
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````
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When run with a single positional argument, it should print the correct article and the given argument.
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````
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$ ./article.py bear
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a bear
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$ ./article.py octopus
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an octopus
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$ ./article.py Octopus
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an Octopus
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````
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The tests will only give you words that start with an actual alphabetic character, so you won't have to detect numbers or punctuation or other weird stuff. Still, how might you extend the program to ensure that given argument only starts with one of the 26 characters of the English alphabest?
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Hints:
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* Start your program with `new.py` and fill in the `get_args` with a single position argument called `word`.
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* You can get the first character of the word by indexing it like a list, `word[0]`.
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* Unless you want to check both upper- and lowercase letters, you can use either the `str.lower` or `str.upper` method to force the input to one case for checking if the first character is a vowel or consonant.
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* There are fewer vowels (five, if you recall), so it's probably easier to check if the first character is one of those.
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* You can use the `x in y` syntax to see if the element `x` is `in` the collection `y` where "collection" here is a `list`.
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* For the purposes of `x in y`, a string (`str`) is a `list` of characters, so you could ask if a character is in a string.
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* Use the `print` function to print out the article joined to the argument. Put a single space in between.
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* Run `make test` (or `pytest -xv test.py`) *after every change to your program*to ensure your program compiles and is on the right track.

‎article/discussion.md‎

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Cf Appendices: argparse, Truthiness
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As with all the solutions presented, this assumes you have stubbed the program with `new.py` and that you are using the `argparse` module. I suggest putting this logic into a separate function which here is called `get_args` and which I like to define first so that I can see right away when I'm reading the program what the program expects as input. On line 12, I set the `description` for the program that will be displayed with the help documentation. On line 15, I indicate that the program expects just one *positional* argument, no more, no less. Since it is a "word" that I expect, I called the argument `word` which is also how I will access the value on line 25. I use the `metavar` on line 15 to let the user know that this should be a string.
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The `get_args` function will `return` the result of parsing the command line arguments which I put into the variable `args` on line 24. I can now access the `word` by call `args.word`. Note the lack of parentheses -- it's not `args.word()` -- as this is not a function call. Think of it like a slot where the value lives.
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'APPLE'
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````
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The `X in Y` form is a way to ask if element `X` is in the collection `Y`:
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The `x in y` form is a way to ask if element `x` is in the collection `y`:
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````
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>>> 'a' in 'abc'
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False
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````
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The `if` *expression* is different from an `if` *statement*. An expression returns a value, and a statement does not. The `if` expression must have an `else`, but the `if` statement does not have this requirement. The first value is returned if the predicate (the bit after the `if`) evaluates to `True` in a Boolean context (cf. "Truthiness"), otherwise the last value is returned:
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The `if` *expression* (also called a "ternary" expression) is different from an `if` *statement*. An *expression* returns a value, and a statement does not. The `if` expression must have an `else`, but the `if` statement does not have this requirement. The first value is returned if the predicate (the bit after the `if`) evaluates to `True` in a Boolean context (cf. "Truthiness"), otherwise the last value is returned:
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````
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>>> 'Hooray!' if True else 'Shucks!'
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article = 'a'
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````
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Cf. appendices: argparse, Truthiness

‎bin/compile.py‎

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fh.write(open(outline).read())
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fh.write('\n\\newpage\n\n')
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for i, dir_name in enumerate(map(str.rstrip, open(chapters)), 1):
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for i, dir_name in enumerate(map(str.rstrip, filter(lambda s: s[0] != '#', open(chapters))), 1):
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print('Chapter {}: {}'.format(i, dir_name))
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readme = os.path.join(in_dir, dir_name, 'README.md')
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if os.path.isfile(readme):

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