code: def get_indexed_string(self, idx):
          
          self._check_device_status()
          bufp = ffi.new("wchar_t*")
          rv = hidapi.hid_get_indexed_string(self._device, idx, bufp, 65536)
          if rv == -1:
              raise IOError("Failed to read string with index {0} from HID "
                            "device: {0}"
                            .format(idx, self._get_last_error_string()))
          return ffi.buffer(bufp, 65536)[:].strip()
docs: Get a string from the device, based on its string index.
  
          :param idx: The index of the string to get
          :type idx:  int
          :return:    The string at the index
          :rtype:     unicode