docs: function avg(line, params) {
  
    var event = params[0];
    var what = params[1];
    var r = Number(line[what]);
    event.what += r;
    ++event.total;
    if (r > event.max) {
      event.max = r;
    }
    if (r < event.min) {
      event.min = r;
    }
    return event;
  }