title: check if record is last or first in list with linq
body: <p>I have a <strong>list of objects</strong>. 
  I want to determine when the user will get the <strong>first or last object in the list</strong>, that way I can disable some buttons on the page.</p>
  
  <p>For example I might have some boolean and if the object requested is last or first in the list, then it will return <code>true</code>, otherwise <code>false</code>.</p>
  
  <p>Any idea? </p>