def open_file(self, url):
        """Use local file or FTP depending on form of URL."""
        if not isinstance(url, str):
            raise IOError, ('file error', 'proxy support for file protocol currently not implemented')
        if url[:2] == '//' and url[2:3] != '/' and url[2:12].lower() != 'localhost/':
            return self.open_ftp(url)
        else:
            return self.open_local_file(url)
dataset/ETHPy150Open kleientertainment/ds_mod_tools/pkg/win32/Python27/Lib/urllib.py/URLopener.open_file/original