@SuppressWarnings("unchecked")
		private static <A, B> B cast(final A value) {
			return (B)value;
		}
Create a writer for genotypes of arbitrary chromosomes. How to write the
genotype chromosomes is defined by the given {@link Writer}.

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