code: def must_contain(tag_name, tag_content, container_tag_name):
      
      def must_contain_closure(element):
          # containing in first level of childs <tag_name> tag
          matching_tags = element.match(tag_name, absolute=True)
          if not matching_tags:
              return False
  
          # which's content match `tag_content`
          if matching_tags[0].getContent() != tag_content:
              return False
  
          # and also contains <container_tag_name> tag
          if container_tag_name and \
             not element.match(container_tag_name, absolute=True):
              return False
  
          return True
  
      return must_contain_closure
docs: Generate function, which checks if given element contains `tag_name` with
      string content `tag_content` and also another tag named
      `container_tag_name`.
  
      This function can be used as parameter for .find() method in HTMLElement.