import tensorflow as tf

          # Build a simple graph.
          v0 = tf.Variable(0.0)
          inc = v0.assign_add(1.0)

          save = tf.train.Saver({"v0": v0})

          # Record a short training history.
          tf.initialize_all_variables().run()
          save.save(sess, filepath, global_step=0)
          inc.eval()
          save.save(sess, filepath, global_step=1)
          inc.eval()
          save.save(sess, filepath, global_step=2)

