docs: function(otherIRs) {
        if (this.model.bounds.isEmpty)
          return;
        var emptyRanges = tr.b.findEmptyRangesBetweenRanges(
            tr.b.convertEventsToRanges(otherIRs),
            this.model.bounds);
        var irs = [];
        var model = this.model;
        emptyRanges.forEach(function(range) {
          // Ignore insignificantly tiny idle ranges.
          if (range.max < (range.min + INSIGNIFICANT_MS))
            return;
          irs.push(new tr.e.rail.IdleInteractionRecord(
              model, range.min, range.max - range.min));
        });
        return irs;
      }