import tensorflow as tf

import os

# Just disables the warning, doesn't enable AVX/FMA
os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
a = tf.constant([1, 2])
b = tf.constant([3, 4])
c = tf.constant([10, 20])
a
<tf.Tensor 'Const_12:0' shape=(2,) dtype=int32>

b
<tf.Tensor 'Const_13:0' shape=(2,) dtype=int32>

d = tf.stack([a, b, c])
with tf.Session() as sess:
    d_val = sess.run(d)
    print(a)
    print(d)
    print(d_val)
Tensor("Const_12:0", shape=(2,), dtype=int32)
Tensor("stack_2:0", shape=(3, 2), dtype=int32)
[[ 1  2]
 [ 3  4]
 [10 20]]

e = tf.stack([a, b, c], axis=1)

with tf.Session() as sess:
    e_val = sess.run(e)
    print(a)
    print(e)
    print(e_val)
Tensor("Const_12:0", shape=(2,), dtype=int32)
Tensor("stack_3:0", shape=(2, 3), dtype=int32)
[[ 1  3 10]
 [ 2  4 20]]