code: public void addValue(Token[] tokens) {
          if (type == null) {
              type = ItemType.LIST;
          }
          if (!isListableType()) {
              throw new IllegalArgumentException("The type of this item must be 'array', 'list' or 'set'");
          }
          if (tokensList == null) {
              tokensList = new ArrayList<>();
          }
          tokensList.add(tokens);
      }
docs: Adds the specified value to this List type item.
  
  @param tokens an array of tokens