code: def get_product_string(self):
          
          self._check_device_status()
          str_p = ffi.new("wchar_t[]", 255)
          rv = hidapi.hid_get_product_string(self._device, str_p, 255)
          if rv == -1:
              raise IOError("Failed to read product string from HID device: {0}"
                            .format(self._get_last_error_string()))
          return ffi.string(str_p)
docs: Get the Product String from the HID device.
  
          :return:    The Product String
          :rtype:     unicode