Cleanup lilypond-book source (issue 583570043 by address@hidden)

[jonas . hahnfeld]

LGTM, thanks for the cleanup!

In the future we might even consider putting all the book_*.py files
into a directory / package. That should make it more natural to import
them.


https://codereview.appspot.com/583570043/diff/545630043/python/book_base_test.py
File python/book_base_test.py (right):

https://codereview.appspot.com/583570043/diff/545630043/python/book_base_test.py#newcode48
python/book_base_test.py:48: self.assertEqual(chunks[-2].line_number,
18)
I'd start counting from the beginning (ie, chunks[7]): When extending
the test in the future, we don't have to recount from the end.

https://codereview.appspot.com/583570043/