docs: public static int[] ConcatenateInt(List<int[]> arrays) {
  
          int size = 0;
          for (int i = 0; i < arrays.size(); i++) {
              size += arrays.get(i).length;
          }
  
          int[] all = new int[size];
          int idx = 0;
  
          for (int i = 0; i < arrays.size(); i++) {
              int[] v = arrays.get(i);
              for (int j = 0; j < v.length; j++) {
                  all[idx++] = v[i];
              }
          }
  
          return all;
      }