RuntimeError: generator raised StopIteration

[quest]

Hello,
I created this class:

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class ssource:     def __init__(self, n):         self.list1=[]         self.list2=[]         self.i=0         self.max=n         self.At=stream(self, self.list1)         self.Bt=stream(self, self.list2)               def __next__(self):         if self.i>=self.max: raise StopIteration         print(f"NEXTSYNC:{self.i}")         self.list1.append(f'A{self.i}')         self.list2.append(f'B{self.i}')         self.i += 1

And I am testing my class with this code script:

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src=ssource(10) Ai=src.Ait Bi=src.Bit   for i in range(5):     print(f'A->{next(Ai)}') for i in range(8):     print(f'B->{next(Bi)}') for a in Ai : print(f'A->{a}')

And I am getting this error:

Error:
NEXTSYNC:0
A->A0
NEXTSYNC:1
A->A1
NEXTSYNC:2
A->A2
NEXTSYNC:3
A->A3
NEXTSYNC:4
A->A4
B->B0
B->B1
B->B2
B->B3
B->B4
NEXTSYNC:5
B->B5
NEXTSYNC:6
B->B6
NEXTSYNC:7
B->B7
A->A5
A->A6
A->A7
NEXTSYNC:8
A->A8
NEXTSYNC:9
A->A9

---------------------------------------------------------------------------
StopIteration                             Traceback (most recent call last)
<ipython-input-36-b322da59c757> in stream(src, fifo)
      4     while True:
----> 5         if len(fifo)==0: next(src)
      6         yield(fifo.pop(0))

<ipython-input-36-b322da59c757> in __next__(self)
     17     def __next__(self):
---> 18         if self.i>=self.max: raise StopIteration
     19         print(f"NEXTSYNC:{self.i}")

StopIteration: 

The above exception was the direct cause of the following exception:

RuntimeError                              Traceback (most recent call last)
<ipython-input-39-9b42e44489d5> in <module>
      7 for i in range(8):
      8     print(f'B->{next(Bi)}')
----> 9 for a in Ai : print(f'A->{a}')

RuntimeError: generator raised StopIteration

here is my another function

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def stream(src, flist):     try:         while True:             while len(flist)==0: next(src)             yield(flist.pop(0))     except StopIteration:         pass #        raise StopIteration

[quest]

Hello again,

I did nothing but now it is ok. I am studying on jupyter notebook maybe because of some connection problems I got this error.

OR If you have any idea, you are very welcome but it is not ok and I do not know how it is ok