code: @Override
  	public boolean isValid() {
  		return !low.equals(NAN)
  				&& !high.equals(NAN)
  				&& (low.compareTo(high) < 0 || (low.compareTo(high) == 0
  						&& lowIncl && highIncl));
  	}
docs: Returns whether it is possible to have normal values (i.e., those other
  than {@link #NEG_INF}, {@link #INF}, and {@link #NAN}) lying within this
  range.