title: I am facing problrm when a run my hello.py file at google apps engine
body: <p>I am facing problrm when a run my hello.py file at google apps engine</p>
  
  <pre><code>import webapp2 
  
  class MainPage(webapp2.RequestHandler): 
      def get(self): 
          self.response.headers['Content-Type'] = 'text/plain'
          self.response.write('Hello, World!')
  
  app = webapp2.WSGIApplication([('/', MainPage), ], debug=True)
  </code></pre>
  
  <blockquote>
    <p>Error: Server Error</p>
    
    <p>The server encountered an error and could not complete your request.
    Please try again in 30 seconds.</p>
  </blockquote>