async function startTimespan(page, options) {
  const {endTimespanGather} = await startTimespanGather(page, options);
  const endTimespan = async () => {
    const gatherResult = await endTimespanGather();
    return Runner.audit(gatherResult.artifacts, gatherResult.runnerOptions);
  };
  return {endTimespan};
}
@param {LH.Puppeteer.Page} page
@param {{config?: LH.Config, flags?: LH.Flags}} [options]
@return {Promise<{endTimespan: () => Promise<LH.RunnerResult|undefined>}>}