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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def setup(self, environ):
        '''Called once to setup the list of wsgi middleware.'''
        json_handler = Root().putSubHandler('calc', Calculator())
        middleware = wsgi.Router('/', post=json_handler,
                                 accept_content_types=JSON_CONTENT_TYPES)
        response = [wsgi.GZipMiddleware(200)]
        return wsgi.WsgiHandler(middleware=[wsgi.wait_for_body_middleware,
                                            middleware],
                                response_middleware=response)