The use of :

[BJörn Lindqvist]

In the faq, http://www.python.org/doc/faq/general.html#why-are-colons-required-for-the-if-while-def-class-statements,
it is stated that the colon is there "primarily to enhance readability
(one of the results of the experimental ABC language)."  But can that
statement really be backed up? Has someone made a study or something?
I always thought the rule was "the less useless symbols, the higher
the readability." I.e:

if (a == b)
{
    print a
}

is less readable than:

if a == b:
    print a

Because it contains more non-significant symbols (, ), { and } that
"steal" the programmers attention. But consider

def f(x, y, z)
    print x, y, z

to

def f(x, y, z):
    print x, y, z

IMHO, the colon-less variant is more readable than the one with the colon.  
  
-- 
mvh Björn