Starts the execution of a generator function or resumes it at the last executed yield expression.

generator. next()

#TODO

#TODO

When a generator function is resumed with a next() method, the current yield expression always evaluates to None. The execution then continues to the next yield expression, where the generator is suspended again, and the value of the expression_list is returned to next()'s caller. If the generator exits without yielding another value, a StopIteration exception is raised.

>>> def gen():
...     yield 1
...     yield 2
...     yield 3
...
>>> g = gen()
>>> g.next()
1
>>> g.next()
2
>>> g.next()
3
>>> g.next()
Traceback (most recent call last):
  File "<interactive input>", line 1, in <module>
StopIteration

#TODO