Parentheses are not required after the assert, del, elif, except, for, if, in, not, raise, return, while, and yield keywords, and using them unnecessarily impairs readability. They should therefore be omitted.

Noncompliant Code Example

x = 1
while (x < 10):
    print "x is now %d" % (x)
    x += 1

Compliant Solution

x = 1
while x < 10:
    print "x is now %d" % (x)
    x += 1