Session and With Block

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.Variable(2)
b = a * 4
b
<tf.Tensor 'mul:0' shape=() dtype=int32>

init_op = tf.initialize_all_variables()
with tf.Session() as session:
    session.run(init_op)
    result = session.run(a + b)
    print(result)
10