async function getState(deviceFeature) {
  const state = await this.client.get(`https://some-api/${deviceFeature.external_id}`);
  return state === true ? STATE.ON : STATE.OFF;
}
@private
@description Get the current state of a device.
@param {object} deviceFeature - The deviceFeature object.
@returns {Promise} Resolving with deviceFeature state.
@example
getState(deviceFeature);