@Override
  public String info(String name) {
    Object struct = db.get(name);
    if (isNull(struct))
      throw new IllegalStateException(format("DB structure with name [%s] does not exist", name));

    if (struct instanceof Set)
      return format("%s - Set - %d", name, ((Set) struct).size());
    else if (struct instanceof List)
      return format("%s - List - %d", name, ((List) struct).size());
    else if (struct instanceof Map)
      return format("%s - Map - %d", name, ((Map) struct).size());
    else
      return format("%s - %s", name, struct.getClass().getSimpleName());
  }
@Test
  void cantGetInfoFromNonexistentDBStructureName() {
    Assertions.assertThrows(IllegalStateException.class, () -> db.info(TEST));
  }