function addDevice(sid, device) {
  const doesntExistYet = this.sensors[sid] === undefined;
  this.sensors[sid] = device;
  if (doesntExistYet) {
    this.gladys.event.emit(EVENTS.WEBSOCKET.SEND_ALL, {
      type: WEBSOCKET_MESSAGE_TYPES.XIAOMI.NEW_DEVICE,
      payload: device,
    });
  }
}
@description Add device.
@param {string} sid - Xiaomi SID.
@param {object} device - Device to add.
@example
xiaomi.addDevice(sid, device);