code: public Set<Node> querySelectorAll(String selectors) throws NodeSelectorException {
          Assert.notNull(selectors, "selectors is null!");
          List<List<Selector>> groups;
          try {
              Scanner scanner = new Scanner(selectors);
              groups = scanner.scan();
          } catch (ScannerException e) {
              throw new NodeSelectorException(e);
          }
  
          Set<Node> results = new LinkedHashSet<Node>();
          for (List<Selector> parts : groups) {
              Set<Node> result = check(parts);
              if (!result.isEmpty()) {
                  results.addAll(result);
              }
          }
  
          return results;
      }
docs: {@inheritDoc}