[SPARK-2470] fix whitespace for doctest
[SPARK-2470] wrap conditionals in parentheses
[SPARK-2470] wrap expression lists in parentheses
[SPARK-2470] style - change position of line break
[SPARK-2470] wrap expression list in parentheses
[SPARK-2470] revert PEP 8 fixes to cloudpickle

Since cloudpickle is a third-party module, we should mostly leave it
alone.

Discussion here:
https://github.com/apache/spark/pull/1505#discussion-diff-15197904