title: Get part of a string modifying the reference of a variable
body: <p>There is a way to return a part of a string and change the reference of a variable. For example:</p>
  
  <pre><code>old_string = 'hello this is a test'
  </code></pre>
  
  <p>A method that returns <code>'Hello'</code>, and <code>old_string</code> becomes <code>'this is a test'</code>.</p>