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I don't understand why D is NOT switched to false when the hand moves left and removes E. At the beginning A is switched to false when the hand moves left over it.

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I watched it again and read the algorithm description part, and I think you're right - D should have been switched to false, as the hand was pointing to it when a cache miss happened.

I watched it again and checked it against the python reference code.

The code and documentation are correct, the animation is wrong.

The behavior is inconsistent with what happens to A and B at the very beginning.

Whenever the hand skips a visited node in search of an unvisited one, it must flip it to unvisited.

If D were given this special treatment every time the hand cycles around, it will forever stay in the cache even if not accessed (D-plomatic immunity?)

Yes; D is spared by the fact that the hand passed over it, but it should be turned gray so that if it is not accessed again by the time the hand comes around again, it will be toasted.

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