code: public static String pointToString (int x, int y) {
          StringBuilder buf = new StringBuilder();
          if (x >= 0) buf.append("+");
          buf.append(x);
          if (y >= 0) buf.append("+");
          buf.append(y);
          return buf.toString();
      }
docs: Returns a string describing the supplied point, of the form {@code +x+y}, {@code +x-y},
  {@code -x-y}, etc.