def _get_cached_style_urls(self, asset_url_path):
        """
        Gets the URLs of the cached styles.
        """
        try:
            cached_styles = os.listdir(self.cache_path)
        except IOError as ex:
            if ex.errno != errno.ENOENT and ex.errno != errno.ESRCH:
                raise
            return []
        except OSError:
            return []
        return [posixpath.join(asset_url_path, style)
                for style in cached_styles
                if style.endswith('.css')]
Gets the URLs of the cached styles.