Parses the content of a response doc into the correct
        format for .state.

def _parse_content(self, text):
        '''Parses the content of a response doc into the correct
        format for .state.
        '''
        try:
            return json.loads(text)
        except ValueError:
            raise exc.UnexpectedlyNotJSON(
                "The resource at {.uri} wasn't valid JSON", self)