title: Python extract numbers from start of string before colon
body: <p>I would like to extract all numbers from the start up to a colon in a string</p>
  
  <pre><code>string = '125: 16272'
  </code></pre>
  
  <p>desired result:</p>
  
  <pre><code>extracted = '125'
  </code></pre>
  
  <p>the numbers will not be negative or contain decimal places, they are just positive integers</p>