how does python3.6 traverse the modification dictionary, adding or deleting a dictionary in each nested dictionary, but it will report an error at run time? how can it not report an error?
A dictionary changed size during iteration exception will be thrown when traversing to modify the key-value pair of adding a dictionary.
Let me give you a simple example:
>>> d={"a":10,"c":5}
>>> for k in d:
... del d[k]
...
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
RuntimeError: dictionary changed size during iterationthis problem can be solved by changing it to a key-value pair:
>>> for k,v in d.items():
... del d[k]
...
>>> d
{}therefore. You just need to modify it a little bit during the loop.
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