title: Split string on first occurrence of separator only
body: <p>The POS tagger that I use processes the following string</p>
  
  <pre><code>3+2
  </code></pre>
  
  <p>as shown below.           </p>
  
  <pre><code>3/num++/sign+2/num
  </code></pre>
  
  <p>I'd like to split this result as follows using python.</p>
  
  <pre><code>['3/num', '+/sign', '2/num']         
  </code></pre>
  
  <p>How can I do that?</p>