title: How to wrap a TF Estimator in a Keras Layer?
body: <p>I have some code already written, using TensorFlow <code>Estimator</code>. </p>
  
  <p>Since I would like to work with Keras (and I need to use the <code>Estimator</code> code), is there any way to wrap the <code>Estimator</code> into a Keras <code>Layer</code> ?</p>