2.9.3. Explanation of less familiar Python statements from Topic 3 – Web

for key, value in info.items():

Found on page 115. info is a dictionary and dict.items() returns a (key, value) pair (a tuple), thus to two items are set in the controlling statement of the for loop.

lamdba astr: '_' + astr, '_string'

Found in the XML-RPC Example. The lamdda keyword allows for a quick way to create a dynamic function object consisting of just a single statement. The above code is a compact version of a function definition of the form:

def _string(astr):
    return '_' + astr

if fd.info().has_keys('Content-Length'):

This line seems unusual because we call a function urllib2.urlopen.info() and then operate on the dictionary item returned. It may have been cleaner to first assigned the dictionary to its own variable (fdinfo = fd.info()), but this works as well.