code: public static int[] c(int[]... x) {
          int n = 0;
          for (int i = 0; i < x.length; i++) {
              n += x.length;
          }
  
          int[] y = new int[n];
          for (int i = 0, k = 0; i < x.length; i++) {
              for (int xi : x[i]) {
                  y[k++] = xi;
              }
          }
          return y;
      }
docs: Merges multiple vectors into one.