code: public static Engine<BitGene, Double> knapsack(
  		final int populationSize,
  		final Random random
  	) {
  		// Search space fo 2^250 ~ 10^75.
  		final Knapsack knapsack = Knapsack.of(250, random);
  
  		// Configure and build the evolution engine.
  		return Engine.builder(knapsack)
  			.populationSize(populationSize)
  			.survivorsSelector(new TournamentSelector<>(5))
  			.offspringSelector(new RouletteWheelSelector<>())
  			.alterers(
  				new Mutator<>(0.03),
  				new SinglePointCrossover<>(0.125))
  			.build();
  	}
docs: Create a new {@link Engine} for solving the {@link Knapsack} problem. The
  engine is used for testing purpose.
  
  @see Knapsack#of(int, Random)
  
  @param populationSize the population size of the created engine
  @param random the random engine used for creating the {@link Knapsack}
  problem instance
  @return a new {@link Knapsack} solving evolution {@link Engine}