Tensorflow gives 0 results

Question

I am learning Tensorflow from this github https://colab.research.google.com/github/instillai/TensorFlow-Course/blob/master/codes/ipython/1-basics/tensors.ipynb#scrollTo=TKX2U0Imcm7d Here is an easy tutorial

import numpy as np
import tensorflow as tf


x = tf.constant([[1, 1],
                 [1, 1]])
y = tf.constant([[2, 4],
                 [6, 8]])

# Add two tensors
print(tf.add(x, y), "\n")

# Add two tensors
print(tf.matmul(x, y), "\n")

What I expect is

tf.Tensor(
[[3 5]
 [7 9]], shape=(2, 2), dtype=int32) 

tf.Tensor(
[[ 8 12]
 [ 8 12]], shape=(2, 2), dtype=int32) 

However, the results are

Tensor("Add_3:0", shape=(2, 2), dtype=int32) 
Tensor("MatMul_3:0", shape=(2, 2), dtype=int32)