docs: public static String toTimeUnit(long millis, int scale) {
  		if (millis < MILLIS_PER_SECOND) {
  			return String.format("%4dms", millis);
  		}
  
  		if (millis < MILLIS_PER_MINUTE) {
  			return String.format("%" + (scale == 0 ? 2 : 3 + scale) + '.' + scale + "fs",
  					millis * 1d / MILLIS_PER_SECOND);
  		}
  
  		if (millis < MILLIS_PER_HOUR) {
  			return String.format("%" + (scale == 0 ? 2 : 3 + scale) + '.' + scale + "fm",
  					millis * 1d / MILLIS_PER_MINUTE);
  		}
  
  		if (millis < MILLIS_PER_DAY) {
  			return String.format("%" + (scale == 0 ? 2 : 3 + scale) + '.' + scale + "fh",
  					millis * 1d / MILLIS_PER_HOUR);
  		}
  
  		return String.format("%" + (scale == 0 ? 2 : 3 + scale) + '.' + scale + "fd", millis * 1d / MILLIS_PER_DAY);
  	}