code: func (d *Data) MakeRange(i, split, procs uint) Range {
  	low := split * i
  	high := low + split - 1
  	if i == procs-1 {
  		high = d.FileSize()
  	}
  
  	return Range{
  		low:    low,
  		high:   high,
  		worker: i,
  	}
  }
docs: // MakeRange will return Range struct to download function