Allows additional representation transformers to be declared for the
        api. Transformers are functions that must be decorated with this
        method, passing the mediatype the transformer represents. Three
        arguments are passed to the transformer:

        * The data to be represented in the response body
        * The http status code
        * A dictionary of headers

        The transformer should convert the data appropriately for the mediatype
        and return a Flask response object.

        Ex::

            @api.representation('application/xml')
            def xml(data, code, headers):
                resp = make_response(convert_data_to_xml(data), code)
                resp.headers.extend(headers)
                return resp

def representation(self, mediatype):
        """Allows additional representation transformers to be declared for the
        api. Transformers are functions that must be decorated with this
        method, passing the mediatype the transformer represents. Three
        arguments are passed to the transformer:

        * The data to be represented in the response body
        * The http status code
        * A dictionary of headers

        The transformer should convert the data appropriately for the mediatype
        and return a Flask response object.

        Ex::

            @api.representation('application/xml')
            def xml(data, code, headers):
                resp = make_response(convert_data_to_xml(data), code)
                resp.headers.extend(headers)
                return resp
        """
        def wrapper(func):
            self.representations[mediatype] = func
            return func
        return wrapper