: ( 648ng)
Black attaches at the left-hand 1-2-point.

:
White gives atari from below, intending a ko fight that Black cannot win.

She could also simplify the issue by descending to , instead. Black would be forced to play at , achieving a gote seki in the corner.

:
Black gives atari at the top, starting the ko fight.

Ko:

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This atari is Black's only remaining adequate ko threat.

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White answers locally.

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White has this ko threat in the centre, threatening to capture Black's upper group at the left.

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Black connects in the upper left corner.

:
White captures for another ko, and will connect at after Black's next move - in principle - killing Black's top left corner.

Black does not have adequate ko threats left.
If he played at , White would let him live at the right. Please note the White does not need to capture the hanezeki's tail after having killed Black's upper left corner, gaining about 25 points from not dissolving the hanezeki alone.
If Black played the atari at , instead, White might answer at , just because she still has an own ko threat at in the lower left corner. Of course, she could also let Black capture some of her stones in the upper right.

White wins the game by a very large margin