title: Where is the source code of Rake tasks in Rails 3?
body: <p>all:</p>
  
  <p>I know how to show all the tasks by typing <code>rake -T</code>, and I know how to add my own tasks by add rake files under RAILS_ROOT/lib/tasks. But if I want to view the source code like <code>rake db:migrate</code> or <code>rake doc:app</code> to see how they work, where can I find those codes?</p>
  
  <p>thank you all :)</p>
  
  <p>eddie</p>