code: public static int randomIntBetween(int lowerBound, int upperBound) {
          if (upperBound < lowerBound) {
              throw new IllegalArgumentException("lower bound higher than upper bound");
          }
          return rand.nextInt(upperBound - lowerBound) + lowerBound;
      }
docs: Returns a random <code>int</code> value out of a specified range
  
  @param lowerBound Lower bound of the target range (inclusive)
  @param upperBound Upper bound of the target range (exclusive)
  @return A random <code>int</code> value out of a specified range