public Collection<XY> neighbors() {
Collection<XY> neighbors = new ArrayList<XY>(4);
for (int i : new int[] {-1, 0, 1}) {
for (int j : new int[] {-1, 0, 1}) {
if (i == 0 ^ j == 0) {
XY neighbor = XY.at(x + i, y + j);
if (neighbor != null) neighbors.add(neighbor);
}
}
}
return neighbors;
}
public void set(int x, int y, ScribeMark mark) {
set(XY.at(x, y), mark);
}