How to use the istanbul-lib-processinfo.ProcessDB function in istanbul-lib-processinfo

}
    tap.parser.on('comment', onComment)
    tap.parser.on('child', onChild)
  }

  tap.runOnly = false

  // greps are passed to children, but not the runner itself
  tap.grep = []
  tap.jobs = options.jobs

  const env = getEnv(options)

  /* istanbul ignore next */
  const processDB = options.coverage && process.env.NYC_CONFIG
    ? new ProcessDB() : null

  // run --before before everything, and --after as the very last thing
  runBeforeAfter(options, env, tap, processDB)

  tap.patchProcess()

  // if not -Rtap, then output what the user wants.
  // otherwise just dump to stdout
  /* istanbul ignore next */
  makeReporter(tap, options)

  // need to replay the first version line, because the previous
  // line will have flushed it out to stdout or the reporter already.
  if (options['output-file'] !== null)
    tap.pipe(fs.createWriteStream(options['output-file'])).write('TAP version 13\n')

async showProcessTree () {
    const db = new ProcessDB(this.processInfo.directory)
    console.log(await db.renderTree(this))
  }

async writeProcessIndex () {
    const db = new ProcessDB(this.processInfo.directory)
    await db.writeIndex()
  }