code: function update(latest) {
      if (latest === null || latest === undefined) {
        isGap = true
        return
      }
  
      if (offset >= latest) {
        return
      }
  
      if (isGap) {
        gaps.push({start: offset, end: latest})
        isGap = false
      }
  
      offset = latest
    }
docs: /* Detect a new position.