Code golf challenge: XKCD 936 passwords

[Roy Smith]

In article <mailman.901.1381334893.18130.python-list at python.org>,
 Nick Cash <nick.cash at npcinternational.com> wrote:

> >> # Python-2, sorry
> >> import os
> >> print list(set(open('/usr/share/dict/words')))[os.getpid():][:4]
> 
> > So that steps by your pid? 
> 
> Not really. It seems to rely on list(set(...)) kinda randomizing order... 
> which is definitely not safe without hash randomization.

Exactly.  I *did* preface this with:

>>> If you're willing to accept a sub-optimal random number generator:

[Nick, again]
> But this brings up an interesting concept... if we can assume Python 2.7 with 
> the -R flag, or Python 3.3+, I think we do get true pseudo-randomization out 
> of list(set(...))... which means we can trim some!
> 
> print(list(set(open('/usr/share/dict/words')))[:4])

Excellent!  I didn't know about -R before this, so not only has this 
been fun, it's been educational too!