title: regex / ng-pattern to accept certain characters
body: <p>I'm using Angular's form validation with <code>ng-pattern</code> to validate a username with Special Charter</p>
  
  <pre><code>ng-pattern="/^[a-z]+@+[a-z]*$/"
  </code></pre>
  
  <p><strong>My problem</strong> is that is limited to only one type of <em>Special Charter</em> to be placed at required place.</p>
  
  <p>I would like this to support any of the special characters we use in alphabets</p>