Try running this line:

print "Yes\n" && exit;
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It probably doesn't do what you think it does. Now try this:

(print "Yes\n") && (exit);
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The problem is, I think, that the first is interpreted as:

print ("Yes\n" && exit);
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If the second operation (exit) is successful then this would print "1" for "true", except that since the second operation is exit it can't print anything because it's exited before it gets to the print statement.