code: public static long sum(long[] array) {
  		if (array == null) {
  			return 0L;
  		}
  		long sum = 0;
  		for (int i = 0; i < array.length; i++) {
  			sum += array[i];
  		}
  		return sum;
  	}
docs: Return the sum of values in the array
  @param array the array to sum
  @return the sum