pep8ify examples/ part 3

``examples/pylab_examples``, ``examples/units`` and ``examples/use_interface`` remain to be done.
@thisch and @WeatherGod: You are both missing the point by stating what you would prefer to see in this situation.  As a community we have agreed that our code should be PEP8 compliant, no more, no less.  According to the relevant PEP8 recommendation, which I quoted above, the code is compliant either with or without the spaces around the multiplication operator.  If the code is already compliant, it should not be altered.