code: async def stepper_step(self, command):
          
          speed = int(command[0])
          num_steps = int(command[1])
          await self.core.stepper_step(speed, num_steps)
docs: This method activates a stepper motor motion.
          This is a FirmataPlus feature.
          :param command: {"method": "stepper_step", "params": [SPEED, NUMBER_OF_STEPS]}
          :returns:No message returned.