default <R1> Generator<T, R1> map(final Function<? super R, ? extends R1> f) {
		requireNonNull(f);
		return cfg -> f.apply(generate(cfg));
	}
Maps the generated result from type {@code R} to type {@code R1}.

@param f the mapping function
@param <R1> the target type
@return a new generator with target type {@code R1}
@throws NullPointerException if the mapping function is {@code null}
jenetics.ext/src/main/java/io/jenetics/ext/grammar/Generator.java