title: Can we get rid of set_session in Tensorflow 2.0?
body: <p>I'm trying to migrate code from Tensorflow 1.13 to Tensorflow 2.0 and I'm having issues with the session declaration step.</p>
  
  <p>For now, I replaced <code>tf.keras.backend.set_session</code> by <code>tf.compat.v1.keras.backend.set_session</code>. </p>
  
  <pre class="lang-py prettyprint-override"><code>config = tf.compat.v1.ConfigProto()
  
  config.gpu_options.allow_growth = True
  if self._gpu_fraction:
      config.gpu_options.per_process_gpu_memory_fraction = self._gpu_fraction
  sess = tf.compat.v1.Session(config=config)
  tf.compat.v1.keras.backend.set_session(sess)
  
  </code></pre>
  
  <p>The code is running but I get a warning:
  <code>The name tf.keras.backend.set_session is deprecated. Please use tf.compat.v1.keras.backend.set_session instead.</code></p>
  
  <p>I understood that sessions evolved a lot with Tensorflow 2 but I'm not sure if I can/should get rid of this <code>set_session</code>.
  I'm also not sure about the warning: is <code>tf.compat.v1.keras.backend.set_session</code> calling the old <code>tf.keras.backend.set_session</code>?</p>
  
  <p>Thank you for any guidance you can provide!</p>