KnowCardPython · Generators & Iterators
An iterator's __next__ has run out of items. How does it signal "no more"?
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More in Generators & Iterators
What does this print?
```
gen = (x*x for x in range(3))
print(sum(gen))
print(sum(gen))
```
What does calling this line do?
```
def squares(n):
for i in range(n):
yield i*i
g = squares(3)
```
What is the key difference in behavior between [x for x in big] and (x for x in big)?
What does this print?
```
i = iter([10, 20])
print(next(i, 'done'))
print(next(i, 'done'))
print(next(i, 'done'))
```
Which methods must an iterator implement, and what ends the iteration?
What does this print?
```
def ab():
yield from ['a', 'b']
yield from ['c']
print(list(ab()))
```
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