Put docstring at start; reduce white spaces in example.

Needs further work to make it epydoc reStructuredText ready.
Fix RST indentation; PEP docstrings; Links for papers cited.

Getting a DOI for many of the papers was harder than usual,
perhaps a temp glitch on the publisher's website?
Fixes for PEP8 W2 whitespace warnings.
Fix PEP8 E711 and E712 (comparisons to True/False/None).
Fixes for PEP8 E241 and E242.
Fixes for PEP8 E3 issues (too few or too many blank lines).
PEP8 fixes for E271 (multiple spaces after keyword).
PEP8 fixes for E231 (missing whitespace after delimiters).
Fix PEP8 E713 issues (test for membership should be ‘not in’)
Fix PEP8 E703 (statement ends with a semicolon).
Fix PEP8 E714 issues (test for object identity should be ‘is not’).
Fix PEP8 E401 issues (multiple imports on one line).