title: Conditional Include in Jade + Express
body: <p>How can one use if -else statement on "include" in jade??</p>
  
  <p>For example, if I have two separate navigation bar templates navbar.jade and navbar_notloggedin.jade</p>
  
  <p>I would like to do:</p>
  
  <pre><code>input(type='hidden', value= user.user)#username
  
  - if(user.user!="")
    include navbar
  - else if(user.user=="")
    include navbar_notloggedin 
  </code></pre>