import tensorflow as tf
x = tf.constant(5, name='x')
y = tf.constant(8, name='y')
z = tf.Variable(2*x+3*y, name='z')
model = tf.global_variables_initializer()

with tf.Session() as sess:
  write = tf.summary.FileWriter("./tf_logs", sess.graph)
  sess.run(model)
  print('z = ', sess.run(z)
# launch tensorboard: tensorboard -logdir=./tf_logs