title: Change key value in Python 3 dictionary using regex
body: <p>Given the following dictionary, how can I return new keys that strip away all non-numbers from the keys? </p>
  
  <pre><code>import re 
  
  dict {'abc_12': 5, 'abc_1': 7, 'abc_34': 10}
  
  for k in dict:
      re.sub('[^0-9]', '', k)
      # change value of first key to '12': 5
  </code></pre>