code: func getMaxMinFromDimensionRef(ref string) (minx, miny, maxx, maxy int, err error) {
  	var parts []string
  	parts = strings.Split(ref, cellRangeChar)
  	minx, miny, err = GetCoordsFromCellIDString(parts[0])
  	if err != nil {
  		return -1, -1, -1, -1, err
  	}
  	maxx, maxy, err = GetCoordsFromCellIDString(parts[1])
  	if err != nil {
  		return -1, -1, -1, -1, err
  	}
  	return
  }
docs: // getMaxMinFromDimensionRef return the zero based cartesian maximum
  // and minimum coordinates from the dimension reference embedded in a
  // XLSX worksheet.  For example, the dimension reference "A1:B2"
  // returns "0,0", "1,1".