code: public double to(final Unit unit) {
  		requireNonNull(unit);
  		return unit.convert(_value, Unit.METERS_PER_SECOND);
  	}
docs: Return the GPS speed value in the desired unit.
  
  @param unit the speed unit
  @return the GPS speed value in the desired unit
  @throws NullPointerException if the given speed {@code unit} is
  {@code null}