title: Dict with multiple values per key sorted by one of the values
body: <p>I have a dictonary of keys, each with nested values with keys/labels. Ik it's a bad explanation, see example below.</p>
  <pre><code>{
  'ATVI': 
      {'momentum': 1695172800449.7812, 'sma': 81.97039999999998}, 
  'ADBE': 
      {'momentum': 15.37463410207528, 'sma': 484.3043000000006}, 
  'AMD': 
      {'momentum': 7.319987019427009e+20, 'sma': 85.5414}
  }
  </code></pre>
  <p>I need to generate a list of the 20 keys which have the highest momentums. What is the best way to do this without affecting the information in this dictionary.</p>