k = rand.nextInt(nBadVariants);
mask = SGFNode.BAD_MOVE;
}
// k = 0 is valid good variant number, so in while it's >= 0
do {
if ((i.current().bits & mask) != 0)
k--;
} while (k >= 0 && i.prevVariant(true) != null);
SGFMove variantMove = i.current().getMoveProperty();
game.play(variantMove.x, variantMove.y, variantMove.color);