title: Write before and after decorator
body: <p>I have following sample code,</p>
  
  <pre><code>def say_hello(f):
      def wrap():
          print "Hello"
      return wrap
  
  def say_bye(f):
      def wrap():
          print "Bye"
      return wrap
  
  @say_hello
  @say_bye
  def process():
      return "Processing"
  
  process()
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>Hello
  </code></pre>
  
  <p>I was expecting output as:</p>
  
  <pre><code>Bye
  Hello
  Processing
  </code></pre>
  
  <ol>
  <li>What could be wrong? </li>
  <li>How to make decorators those will be called before and after function call?</li>
  </ol>
  
  <p>Means, with above example, Can I have output:</p>
  
  <pre><code>    Hello
      Processing
      Bye 
  </code></pre>