title: Find string between two substrings
body: <p>How do I find a string between two substrings (<code>'123STRINGabc' -&gt; 'STRING'</code>)?</p>
  
  <p>My current method is like this:</p>
  
  <pre><code>&gt;&gt;&gt; start = 'asdf=5;'
  &gt;&gt;&gt; end = '123jasd'
  &gt;&gt;&gt; s = 'asdf=5;iwantthis123jasd'
  &gt;&gt;&gt; print((s.split(start))[1].split(end)[0])
  iwantthis
  </code></pre>
  
  <p>However, this seems very inefficient and un-pythonic. What is a better way to do something like this?</p>
  
  <p>Forgot to mention:
  The string might not start and end with <code>start</code> and <code>end</code>. They may have more characters before and after.</p>