add method
Implementation
void add(Label lbl) {
for (int i = 0; i < 2; i++) {
for (int j = 1; j < 3; j++) {
int loc = lbl.getLocationWithPosIndex(i, j);
if (loc == Location.EXTERIOR || loc == Location.INTERIOR) {
// initialize depth if it is null, otherwise add this location value
if (isNull2(i, j)) {
depth[i][j] = depthAtLocation(loc);
} else
depth[i][j] += depthAtLocation(loc);
}
}
}
}