code: function load (robot) {
    robot.respond(/^(sync users with brain|sync brain users)/i, async (res) => {
      const addedUsers = await syncBrainUsers(robot)
      if (typeof addedUsers === 'undefined') {
        res.reply(`Sorry I can't do that.`)
      } else {
        const names = '@' + addedUsers.join(', @').replace(/,(?!.*,)/gmi, ' and')
        res.reply(`${names} were added to my brain.`)
      }
    })
  }
docs: Add command for bot to respond to requests for brain sync with added users.
  e.g. "bot sync brain users" or "@bot sync users with brain"
  @param {Robot} robot The Hubot instance