title: AttributeError: module 'tensorflow' has no attribute 'Session'
body: <p>When I call any function in <code>python3.6</code>, I get the error below; however, it works fine in <code>python3.4</code>. Any idea? 
  <code>import tensorflow as tf 
  tf.Session()</code>
  Traceback (most recent call last):
    File "", line 1, in 
  AttributeError: module 'tensorflow' has no attribute 'Session'</p>
  
  <blockquote>
    <p>Here is my  System information</p>
  </blockquote>
  
  <ul>
  <li><strong>OS Platform and Distribution (e.g., Linux Ubuntu 16.04)</strong>: Debian 8.7 </li>
  <li><strong>TensorFlow installed from (source or binary)</strong>: by pip3</li>
  <li><strong>TensorFlow version (use command below)</strong>: 1.7.0</li>
  <li><strong>Python version</strong>: 3.6.5</li>
  <li><strong>CUDA/cuDNN version</strong>: cuda 9.0 and cudnn 7.0</li>
  <li><strong>GPU model and memory</strong>: K80, 12 GB </li>
  <li><strong>Exact command to reproduce</strong>:
  import tensorflow as tf 
  tf.Session()</li>
  </ul>