pep8: fix indentation issues inside functions
pep8: put spaces around operator
Anomalous backslash in string: '\s'. String constant might be missing an r prefix.
Idiomatic python: initialization of object with defaults
Idiomatic python: initialization of object with defaults
Idiomatic python: use list comprehension
Idiomatic python: use filter() on sequence to remove empty strings
Add comment to show we are dropping empty strings