title: Extract indexes from multi-hot vector in Tensorflow
body: <p>How to extract indexes from multi-hot tensor in Tensorflow?</p>
  
  <p>For examples,</p>
  
  <pre><code>a = (1, 1, 0, 1, 0, 0, 0)
  </code></pre>
  
  <p>Then, output should be</p>
  
  <pre><code>output = (0, 1, 3)
  </code></pre>