code: function load (robot) {
    robot.respond(/\b(clean room|clr)( from (.*))?(\.|!|)?$/i, async (res) => {
      try {
        const from = res.match[3] || 'May 19, 2015 04:36:09' // clear all if not given date
        const oldest = new Date(from).toISOString()
        const cleaned = await cleanRoomHistory(robot, res.message.user, oldest).catch()
        if (typeof cleaned === 'undefined') {
          res.reply(`Sorry, I'm afraid I can't do that.`)
        }
      } catch (err) {
        res.reply(`That wasn't a valid date`)
      }
    })
  }
docs: Add command for bot to clear the room history (requires client reload).
  e.g. "bot clr" or "@bot clear room" or "bot clr from June 3, 2018 17:30".
  @param {Robot} robot The Hubot instance