code: @Override public synchronized String lindex(final String key, long index) throws WrongTypeException {
          if (!exists(key)) {
              return null;
          }
          checkType(key, "list");
          if (index < 0) {
              index = listCache.get(key).size() + index;
          }
          try {
              return listCache.get(key).get((int)index);
          }
          catch (IndexOutOfBoundsException e) {
              return null;
          }
      }
docs: /* IRedisList implementations