title: How to update tf.contrib.layers.real_valued_column code to tf 2.0
body: <p>I came across a Gaussian Kernel classifier tutorial in Python that utilizes tensorflow. In part of the tutorial,  <code>tf.contrib.layers.real_valued_column</code> is referenced. However, as far as I know,  <code>tf.contrib</code> is deprecated.</p>
  <p>How can I change the statement to work in <code>tensorflow 2.0</code> ?</p>
  <p>I tried using  <code>tf_slim</code> and  <code>tf.keras</code>, but I was unable to find the equivalent statements. Thanks in advance.</p>