def getEncoder(self, request):
        """
        Browser the list of encoders looking for one applicable encoder.
        """
        for encoderFactory in self._encoders:
            encoder = encoderFactory.encoderForRequest(request)
            if encoder is not None:
                return encoder

        Browser the list of encoders looking for one applicable encoder.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/resource.py