code: public static void assertSameLength(INDArray x, INDArray z) {
          val lengthX = x.length();
          val lengthZ = z.length();
          if (lengthX != lengthZ && lengthX != 1 && lengthZ != 1)
              throw new IllegalStateException("Mis matched lengths: [" + x.length() + "] != [" + z.length() + "] - " +
                      "Array 1 shape: " + Arrays.toString(x.shape()) + ", array 2 shape: " + Arrays.toString(z.shape()));
      }
docs: Asserts both arrays be the same length
  @param x
  @param z