code: def getString(self, index, length, langid = None):
          r
          return util.get_string(self.dev, index, langid).encode('ascii')
docs: r"""Retrieve the string descriptor specified by index
              and langid from a device.
  
          Arguments:
              index: index of descriptor in the device.
              length: number of bytes of the string (ignored)
              langid: Language ID. If it is omitted, the first
                      language will be used.