Variable scope in comprehensions

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Accepted Answer

In Python 3, list comprehensions have their own scope — the loop variable does not leak into the enclosing scope. This is a deliberate fix from Python 2, where it did leak. Regular for loops still leak: after 'for x in range(5): pass', x is 4. But comprehension variables are local to the comprehension. This is one of the subtle Python 2 vs Python 3 differences that trips up developers who learned on Python 2.