title: The print of string constant is always attached with 'b' inTensorFlow
body: <p>Durng the test of TensorFlow r0.12(CPU) installed on Windows 10, I found that the printed string contant is always with an 'b' in the end. The print of python is normal. I cannot figure out the reason so came here for help. The code is as follows:</p>
  
  <pre><code>&gt;&gt;&gt;import tensorflow as tf
  &gt;&gt;&gt;hello = tf.constant('Hello, TensorFlow!')
  &gt;&gt;&gt;sess = tf.Session()
  &gt;&gt;&gt;print(sess.run(hello))
  b'Hello, TensorFlow!'
  </code></pre>