python generator

>>> lst_num = [1,2,3] 
>>> iter = (i for i in lst_num) 
>>> print iter.next 
<method-wrapper 'next' of generator object at 0xb71566e4> 
>>> print iter.next() 
1 
>>> print iter.next() 
2 
>>> print iter.next() 
3 
>>> print iter.next() 
Traceback (most recent call last): 
  File "<stdin>", line 1, in <module> 
StopIteration 

>>> def use_yield(): 
...    for i in range(10): 
...      yield(i) 
...  
>>>  
>>> iter = use_yield() 
>>> iter.next() 
0 
>>> iter.next() 
1 
>>> iter.next() 
2 

>>> def use_send(): 
...   print 'how are you?', 
...   m = yield('55555') 
...   print m 
...   n = yield('aaaaaaaaaaa') 
...   print 'ok!' 
...  
>>> test = use_send() 
>>> test.send(None) 
how are you? 
'55555' 
>>> test.next() 
None 
'aaaaaaaaaaa' 
>>> test.next() 
ok! 
Traceback (most recent call last): 
  File "<stdin>", line 1, in <module> 
StopIteration 
>>> test = use_send() 
>>> test.next() 
how are you? 
'55555' 
>>> test.send('fine,3Q.') 
fine,3Q. 
'aaaaaaaaaaa' 

m = yield('55555')  
相当于下面伪代码
print(‘55555’)       //输出55555
m = wait_and get()   //等待输入，并把值返给m,另外告诉next() = send(None)