code: def getPortNumberList(self):
          
          port_list = (c_uint8 * PATH_MAX_DEPTH)()
          result = libusb1.libusb_get_port_numbers(
              self.device_p, port_list, len(port_list))
          mayRaiseUSBError(result)
          return list(port_list[:result])
docs: Get the port number of each hub toward device.