Generator expressions and buildin functions : Generator « Statement « Python Tutorial

print sum(x ** 2 for x in range(4))
print sorted(x ** 2 for x in range(4))
print sorted((x ** 2 for x in range(4)), reverse=True)
import math
print map(math.sqrt, (x ** 2 for x in range(4)))

3.18.1.Generator Expressions: Iterators Meet List Comprehensions
3.18.2.generator expressions return a generator object, which in turn supports the iteration protocol to yield one piece of the result list at a time in any iteration context
3.18.3.Generator expressions and buildin functions
3.18.4.Generator Function Example
3.18.5.use any of the for loop, map, or list comprehension techniques: