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What should be done with accepted, yet wrong, answers?
In this particular case the OP accepted an answer that, by all means, was wrong. And when I say "wrong," I don't mean that it could be done by a better approach. I mean simple, plain, wrong.
More on that: the user was warned in advance that the answer was wrong.
Clearly, this devalues the site.
How should one act upon answers like this? Flag them for moderation?