docs: static Map<String, knucleotide> sumTwoMaps(Map<String, knucleotide> map1, Map<String, knucleotide> map2) {
          for (Map.Entry<String, knucleotide> entry : map2.entrySet()) {
              knucleotide sum = (knucleotide)map1.get(entry.getKey());
              if (sum != null)
              sum.count += entry.getValue().count;
              else
              map1.put(entry.getKey(), entry.getValue());
          }
          return map1;
      }