Tabs and spaces (style)

[Tim Peters]

I see Guido used his time machine to ensure that his Style Guide has *never*
recommended mixing tabs and spaces.  Cool!

Code in the distributed standard library uses 4-space indents and no hard tab
characters anywhere (not even in comments).  This is enforced via running

    Tools/scripts/reindent.py

over the Lib/ directory from time to time.  You're also allowed to use it.