code: async def keep_alive(self, command):
          
          period = int(command[0])
          margin = int(command[1])
          await self.core.keep_alive(period, margin)
docs: Periodically send a keep alive message to the Arduino.
          Frequency of keep alive transmission is calculated as follows:
          keep_alive_sent = period - (period * margin)
  
          :param command:  {"method": "keep_alive", "params": [PERIOD, MARGIN]}
          Period is time period between keepalives. Range is 0-10 seconds. 0 disables the keepalive mechanism.
          Margin is a  safety margin to assure keepalives are sent before period expires. Range is 0.1 to 0.9
          :returns: No return value