Thank you.  I've added that.  

This may seem like an odd question, but should I assume that the docs should always match the code?  For example, in the Functional HOWTO, I wasn't sure if the arguments were left off purposely or if it was just something that hadn't been updated.  If the docs should always match, then I wouldn't have to ask so many questions if I see another place where this happens.

Also, the example for enumerate is this:

f = open('data.txt', 'r')
for i, line in enumerate(f):
    if line.strip() == '':
        print('Blank line at line #%i' % i)

Is it code churn to replace the old style string formatting or is that something else that should be done as clean-up?