code: @Pure
  	public static double toSeconds(double value, TimeUnit inputUnit) {
  		switch (inputUnit) {
  		case DAYS:
  			return value * 86400.;
  		case HOURS:
  			return value * 3600.;
  		case MINUTES:
  			return value * 60.;
  		case SECONDS:
  			break;
  		case MILLISECONDS:
  			return milli2unit(value);
  		case MICROSECONDS:
  			return micro2unit(value);
  		case NANOSECONDS:
  			return nano2unit(value);
  		default:
  			throw new IllegalArgumentException();
  		}
  		return value;
  	}
docs: Convert the given value expressed in the given unit to seconds.
  
  @param value is the value to convert
  @param inputUnit is the unit of the {@code value}
  @return the result of the convertion.