title: What does a trailing colon mean in the name of a Rake task?
body: <p>In the custom Rake task example:</p>
  
  <pre><code>desc "I am short, but comprehensive description for my cool task"
  task task_name: [:prerequisite_task, :another_task_we_depend_on] do
    # All your magic here
    # Any valid Ruby code is allowed
  end
  </code></pre>
  
  <p>What does the colon suffix after <code>task_name</code> indicate? Normally, the task name is a symbol - what's different about this if you have prerequisites?</p>