title: What is the meaning behind "WARNING:tensorflow:Passing a `GraphDef` to the SummaryWriter is deprecated"?
body: <p>What is the meaning behind that warning? I'd love it if someone could explain what a Graph object is and why passing sess.graph_def shouldn't be done.</p>
  
  <pre><code>summary_writer = tf.summary.FileWriter('logistic_logs/',graph_def=sess.graph_def)
  </code></pre>