/**
  * Unmarshall a Genotype instance from a given XML Element representation. Its population of
  * Chromosomes will be unmarshalled from the Chromosome sub-elements.
  *
  * @param a_activeConfiguration the current active Configuration object that is to be used during
  *     construction of the Genotype and Chromosome instances
  * @param a_xmlElement the XML Element representation of the Genotype
  * @return a new Genotype instance, complete with a population of Chromosomes, setup with the data
  *     from the XML Element representation
  * @throws ImproperXMLException if the given Element is improperly structured or missing data
  * @throws InvalidConfigurationException if the given Configuration is in an inconsistent state
  * @throws UnsupportedRepresentationException if the actively configured Gene implementation does
  *     not support the string representation of the alleles used in the given XML document
  * @throws GeneCreationException if there is a problem creating or populating a Gene instance
  * @author Neil Rotstan
  * @author Klaus Meffert
  * @since 1.0
  */
 public static Genotype getGenotypeFromElement(
     Configuration a_activeConfiguration, Element a_xmlElement)
     throws ImproperXMLException, InvalidConfigurationException,
         UnsupportedRepresentationException, GeneCreationException {
   // Sanity check. Make sure the XML element isn't null and that it
   // actually represents a genotype.
   if (a_xmlElement == null || !(a_xmlElement.getTagName().equals(GENOTYPE_TAG))) {
     throw new ImproperXMLException(
         "Unable to build Genotype instance from XML Element: "
             + "given Element is not a 'genotype' element.");
   }
   // Fetch all of the nested chromosome elements and convert them
   // into Chromosome instances.
   // ------------------------------------------------------------
   NodeList chromosomes = a_xmlElement.getElementsByTagName(CHROMOSOME_TAG);
   int numChromosomes = chromosomes.getLength();
   Population population = new Population(a_activeConfiguration, numChromosomes);
   for (int i = 0; i < numChromosomes; i++) {
     population.addChromosome(
         getChromosomeFromElement(a_activeConfiguration, (Element) chromosomes.item(i)));
   }
   // Construct a new Genotype with the chromosomes and return it.
   // ------------------------------------------------------------
   return new Genotype(a_activeConfiguration, population);
 }