Trivial generators example

gistfile1.txt

>>> def gen():
...     yield 1
...     yield 2
...     yield 3
... 
>>> for i in gen():
...     print i
... 
1
2
3

>>> def gen():
...     print "starting"
...     yield 1
...     yield 2
...     yield 3
...     print "done"
... 
>>> for i in gen():
...     print "from gen:", i
... 
starting
from gen: 1
from gen: 2
from gen: 3
done