Today's just-for-fun experiment: encode a set of integers (usually seen as 
`?whtvr=3,7,8,9,11...` in urls) into a string. Sure, just doing `','.join` 
on a set works, but the result's ugly¹. Such stuff in urls was, I believe, 
one of the reasons Opera 11 decided to hide all parameters in address bar 
by default. Urls look better without cruft.
So instead, I'd like to have something short and 
with letters in it. Something that looks like it could be a part of those 
"shortened urls" (i.e. <http://goo.gl/Gmzqv>²).
How about encoding the set with base64?
    :::python
    '3,7,8,9,11,12,13,16,23,27,30,33'.encode('base64')
    # 'Myw3LDgsOSwxMSwxMiwxMywxNiwyMywyNywzMCwzMw==\n'
Gah! This just doesn't work. But hey, what we encoded here is not *the set*, 
it's a *string representation* of the set! How about ditching this string 
and think of other structure to represent sets. Hmm, what could it be? 
Hint: it's in the experiment title, duh.
¹: although it's also easier to debug
²: you can check real location without visiting short url with 
   `curl --head <url> | grep Location`
Requirements
------------
Python (2 or 3), [bitarray].
[bitarray]: http://pypi.python.org/pypi/bitarray/