Log Message:
py-jaraco.itertools: updated to 6.2.1

v6.2.1
======
Fixed broken test in ``ensure_unique``.

v6.2.0
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Added ``accumulate`` function.

v6.1.1
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Fixed typo in ``ensure_unique`` doctest.

v6.1.0
======
Add ``ensure_unique`` function.

v6.0.3
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Fixed doc build errors.

v6.0.2
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Minor fixes.

v6.0.1
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Switch to PEP 420 for namespace package.

v6.0.0
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Remove ``Counter.GetCount``.
Remove ``flatten`` and ``iflatten``.