A gotcha with the Walrus operator
In New python syntax I was previously unaware of, I discussed some new operators I'd recently discovered. One of them is called the Walrus operator, which lets you write code like this: list = ['a', 'b', 'c'] def get_one(): if not list: return None return list.pop() while one := get_one(): print(one) See where we do the assignment inside the while? That code returns: c b a Which is as expected. However, the Walrus operator is strict about needing a None returned to end the iteration. I had code which was more like this: list = [('a', 1), ('b', 2), ('c', 3)] def get_one(): if not list: return None, None return list.pop() while one := get_one(): print(one) And the while loop never terminates. It just prints (None, None) over and over. So there you go.