new_contents: import os.path
  import sys
  
  sys.path.insert(0, os.path.abspath(os.path.dirname(__file__) + '/../../src'))
  
  from app import Application
  
  
  def extended_hello(request):
      return request.Response(text='Hello ' + request.reversed_agent)
  
  
  def reversed_agent(request):
      return request.headers['User-Agent'][::-1]
  
  
  app = Application()
  app.extend_request(reversed_agent, property=True)
  
  r = app.router
  r.add_route('/', extended_hello)
  
  
  app.serve()
  
subject: extend example