cleanup: use list comprehensions It's often the same number of lines, but avoids introducing a needless "result" variable, and makes the item expression stand out more clearly. It's also a tiny bit faster, but the readability gains is what matters.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.