If you saw a man hitting a woman in public, what, if anything, would you do?

If you were standing on a sidewalk outside a restaurant and you saw a man and a woman arguing, and the man began hitting the woman, what, if anything, would you do?

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I would do absolutely nothing except walk on by. It's her problem, not mine, and I am under no obligation to risk my life and limb to deend some woman who wouldn't appreciate it anyway. That big, strong, tough woman who doesn't need a man can just defend herself.
If you saw a man hitting a woman in public, what, if anything, would you do?
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