title: How to read Keras checkpoint in tensorflow?
body: <p>I used <code>ch_callback = ModelCheckpoint('./foo.bar')</code> with my <code>model.fit()</code>. And I got exactly what I requested, namely a <code>'./foo.bar'</code> file. </p>
  
  <ul>
  <li>What format does it actually have? </li>
  <li>How can this checkpoint be used, where can I load it? </li>
  <li>Most importantly, can I convert it to native tensorflow checkpoint format?</li>
  </ul>