code: public static int find(int[] arr, int start, int end, int valueToFind) {
      assert arr != null;
      assert end >= 0;
      assert end <= arr.length;
  
  
      for (int i = start; i < end; i++) {
        if (arr[i] == valueToFind) {
          return i;
        }
      }
  
      return NOT_FOUND;
    }
docs: Finds a value in an int array.
  
  @param arr the target array
  @param start the inclusive initial value to check
  @param end the exclusive end value to check
  @param valueToFind the value to find
  @return the index1 or NOT_FOUND