title: ruby, using regex to find something in between two strings
body: <p>Using Ruby + regex, given:</p>
  
  <p><code>starting-middle+31313131313@mysite.com</code></p>
  
  <p>I want to obtain just: <code>31313131313</code></p>
  
  <p>ie, what is between <code>starting-middle+</code> and <code>mysite.com</code></p>
  
  <p>Here's what I have so far:</p>
  
  <pre><code>to = 'starting-middle+31313131313@mysite.com'
  
  to.split(/\+/@mysite.com.*/).first.strip
  </code></pre>