def thing():

print("starting")

print("blah blah blah")

print("yielding 1")

yield 1

print("running")

print("blah blah blah")

print("yielding 2")

yield 2

print("done")

t = Thing() # run nothing at all

print("got from next(t):", next(t)) # run the first piece

print("got from next(t):", next(t)) # run the second piece

print("got from next(t):", next(t)) # run the last piece and raise StopIteration

We have used for loops in many exercises and other things so far. One of

the simplest things we can for loop over are lists.

>>> for item in ['a', 'b', 'c']:

... print(item)

...

a

b

c

>>>

But what exactly is happening behind the scenes?

An **iterable** is anything we can put after a `for item in`. For

example, strings, lists, tuples and dictionaries are all iterable.

Iterating over an iterable is simple:

string = 'hello'

for character in string:

print(character)

You might think that under the covers Python does something like this:

string = 'hello'

index = 0

while index < len(string):

print(string[index])

index += 1

But actually, th

def thing():

print("starting")

print("blah blah blah")

print("yielding 1")

yield 1

print("running")

print("blah blah blah")

print("yielding 2")

yield 2

print("done")

t = Thing() # run nothing at all

print("got", next(t)) # run the first piece

print("got", next(t)) # run the second piece

print("got", next(t)) # run the last piece and raise StopIteration