How to use the pyquery.openers.url_opener function in pyquery

else:
            self._translator = self._translator_class(xhtml=False)

        self.namespaces = kwargs.pop('namespaces', None)

        if kwargs:
            # specific case to get the dom
            if 'filename' in kwargs:
                html = open(kwargs['filename'])
            elif 'url' in kwargs:
                url = kwargs.pop('url')
                if 'opener' in kwargs:
                    opener = kwargs.pop('opener')
                    html = opener(url, **kwargs)
                else:
                    html = url_opener(url, kwargs)
                if not self.parser:
                    self.parser = 'html'
                self._base_url = url
            else:
                raise ValueError('Invalid keyword arguments %s' % kwargs)

            elements = fromstring(html, self.parser)
            # close open descriptor if possible
            if hasattr(html, 'close'):
                try:
                    html.close()
                except Exception:
                    pass

        else:
            # get nodes