public static <G extends Gene<?, G>, C extends Comparable<? super C>>
	Evaluator<G, C>
	async(final Function<? super Genotype<G>, ? extends Future<C>> fitness) {
		return new FutureEvaluator<>(fitness);
	}
Return a new fitness evaluator, which evaluates <em>asynchronous</em>
fitness functions.

@see #completable(Function)

@param fitness the asynchronous fitness function
@param <G> the gene type
@param <C> the fitness value type
@return a new (asynchronous) fitness evaluator
@throws NullPointerException if one of the arguments is {@code null}
jenetics/src/main/java/io/jenetics/engine/Evaluators.java