Populating a list using append()

Populating a list using append()

What is the right way to populate a list? I have my code below but it doesn't seem to work.

$(document).ready(function(){
   var a = 'Yup. ';
   $('a').click(function(){
      $('ul').append('<li><strong>' + a + '</strong>You\'re the boss.</li>').
   });
});