public static <A> Writer<io.jenetics.PermutationChromosome<A>>
		writer(final Writer<? super A> alleleWriter) {
			return Writer.<io.jenetics.PermutationChromosome<A>>elem(
				ROOT_NAME,
				attr(LENGTH_NAME).map(io.jenetics.PermutationChromosome::length),
				elem(VALID_ALLELES_NAME,
					attr("type").map(PermutationChromosome::toAlleleTypeName),
					Writer.<A>elems(ALLELE_NAME, alleleWriter)
						.map(io.jenetics.PermutationChromosome::validAlleles)
				),
				elem(ORDER_NAME, text())
					.map(ch -> ch.stream()
						.map(g -> Integer.toString(g.alleleIndex()))
						.collect(Collectors.joining(" ")))
			);
		}
Create a writer for permutation-chromosomes. How to write the valid
alleles is defined by the given {@link Writer}.

@param alleleWriter the allele writer
@param <A> the allele type
@return a new permutation chromosome writer
@throws NullPointerException if the given allele {@code writer} is
        {@code null}
jenetics.xml/src/main/java/io/jenetics/xml/Writers.java