Please help

Lists, sets, and dictionaries are all mutable. Although we can execute code that changes the length of a list while it is being iterated over (by calling append or del), Python does not allow us to change the lengths of a set or dict while either is being iterated over. When Python runs the following code s = set([1]) for i in s: s.add(2) # this line raises: RuntimeError: Set changed size during iteration

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