formatMilliseconds (millisec) {
    const seconds = (millisec / 1000).toFixed(1)
    const minutes = (millisec / (1000 * 60)).toFixed(1)
    const hours = (millisec / (1000 * 60 * 60)).toFixed(1)
    const days = (millisec / (1000 * 60 * 60 * 24)).toFixed(1)
    if (seconds < 60) {
      return seconds + ' seconds'
    } else if (minutes < 60) {
      return minutes + ' minutes'
    } else if (hours < 24) {
      return hours + ' hours'
    } else {
      return days + ' days'
    }
  }
inspired from https://stackoverflow.com/questions/19700283/how-to-convert-time-milliseconds-to-hours-min-sec-format-in-javascript
@param millisec
@returns {string}