def next(iterator, default=None): # real signature unknown; restored from __doc__
"""
next(iterator[, default])
Return the next item from the iterator. If default is given and the iterator
is exhausted, it is returned instead of raising StopIteration.
"""
pass
从迭代器返回下一个项目。 如果给出了默认值并且迭代器
已耗尽，则返回而不是引发 StopIteration。