docs: def check_serial_port(name):
      """returns valid COM Port."""
      try:
          cdc = next(serial.tools.list_ports.grep(name))
          return cdc[0]
      except StopIteration:
          msg = "device {} not found. ".format(name)
          msg += "available devices are: "
          ports = list(serial.tools.list_ports.comports())
          for p in ports:
              msg += "{},".format(text_type(p))
          raise ValueError(msg)