title: Cannot import name 'tf2'
body: <p>I created a <code>v.environment</code> where I have Python version 3.6.5 and there I installed <code>tensorflow-gpu</code>.<br />
  The version of TensorFlow is 1.4.0 and of Keras is 2.6.0.<br />
  When I write on the script <code>import keras</code> it appears the following Error:</p>
  <blockquote>
  <p>ImportError: cannot import name 'tf2'</p>
  </blockquote>
  <p>Have you any idea?</p>