docs: def extra_info(self):
          """Retrieve the log string generated when opening the file."""
          info = _ffi.new("char[]", 2**14)
          _snd.sf_command(self._file, _snd.SFC_GET_LOG_INFO,
                          info, _ffi.sizeof(info))
          return _ffi.string(info).decode('utf-8', 'replace')