SymbolIndex get(final Genotype<IntegerGene> gt) {
			final var codons = new CodonsCache(gt);

			return (rule, bound) -> codons
				.get(_rulesIndex.get(rule.start().name()))
				.next(rule, bound);
		}
Helper class for generating codons for a given genotype.
jenetics.ext/src/main/java/io/jenetics/ext/grammar/MultiIntegerChromosomeMapper.java