message: Fix typo in summary example code
  Summary: Also a drive-by Python 2 -> 3 fix
  Reviewers: #tensorflow, davidn
diff: @@ -83,10 +83,10 @@ graph, or the train op for a training graph.
  f = tf.summary.FileWriter('logs')
  with tf.Session() as s:
  - sum_out, ... = s.run([add_sum, ...])
  + sum_out, ... = s.run([all_sum, ...])
  f.add_summary(sum_out, 0)
  - print "c = " + str(c)
  + print("c = {}".format(c))
  Enabling tracing in the hardware configuration options
  