title: check if there are non-letters or non-numbers in the string
body: <p>How can I detect a non number or non letter on a string?</p>
  <p><code>KY4R5EHCN5W476XXO5ER</code> - return <code>true</code></p>
  <p><code>KY4R5EHCN5W472X**@**O5ER</code> - return <code>false</code></p>
  <p>I know the answer is to use a regular expression, I just don't know how to do it. I suck at regular expressions.  Any help will be appreciated.</p>
  <p>Thanks!</p>