code: func binSearchRuns(v uint16, a []interval16) (int32, bool) {
  	i := int32(sort.Search(len(a),
  		func(i int) bool { return a[i].last >= v }))
  	if i < int32(len(a)) {
  		return i, (v >= a[i].start) && (v <= a[i].last)
  	}
  
  	return i, false
  }
docs: // binSearchRuns returns the index of the run containing v, and true, when v is contained;
  // or the index of the next run starting after v, and false, when v is not contained.