/**
  * @param a_gene Gene
  * @param a_xmlDocument Document
  * @return Element
  * @author Klaus Meffert
  * @since 2.0
  */
 private static Element representAlleleAsElement(final Gene a_gene, final Document a_xmlDocument) {
   Element alleleElement = a_xmlDocument.createElement(ALLELE_TAG);
   alleleElement.setAttribute("class", a_gene.getClass().getName());
   alleleElement.setAttribute("value", a_gene.getPersistentRepresentation());
   return alleleElement;
 }