Python yield Statement Tutorial

def producesList(xs):
    ys = []
    for x in xs:
        if x % 4 == 0:
            continue
        if x % 2 == 0:
            ys.append(x * 3)
    return ys
    
def generator(xs):
    for x in xs:
        if x % 4 == 0:
            continue
        if x % 2 == 0:
            yield x * 3

print '-- producesList'
for x in producesList(range(10)):
    print x
print '-- generator'
for x in generator(range(10)):
    print x
xs = range(5)
xs.extend(producesList(range(10)))
print '-- producesList'
print xs
ys = range(5)
ys.extend(generator(range(10)))
print '-- generator'
print ys

The output...

$ python ~/Documents/py/yield_tutorial.py 
-- producesList
6
18
-- generator
6
18
-- producesList
[0, 1, 2, 3, 4, 6, 18]
-- generator
[0, 1, 2, 3, 4, 6, 18]