pep8: Use of None
pep8: Blank lines

Use 2 lines to separate top-level functions and classes, 1 to separate
methods.
pep8: Spaces after =
pep8: Multiple statements in a single line
pep8: Inline comments
pep8: comment out unused vars
FencedCode: Drop a redundant attr setting
pep8: Condition alignment
pep8: Spaces around default assignment