code: public function startElement($name, $attributes)
      {
          $factory = new SimpleTagBuilder();
          $tag     = $factory->createTag($name, $attributes);
          if (! $tag) {
              return true;
          }
          if ($tag->getTagName() === 'label') {
              $this->acceptLabelStart($tag);
              $this->openTag($tag);
  
              return true;
          }
          if ($tag->getTagName() === 'form') {
              $this->acceptFormStart($tag);
  
              return true;
          }
          if ($tag->getTagName() === 'frameset') {
              $this->acceptFramesetStart($tag);
  
              return true;
          }
          if ($tag->getTagName() === 'frame') {
              $this->acceptFrame($tag);
  
              return true;
          }
          if ($tag->isPrivateContent() && ! isset($this->private_content_tag)) {
              $this->private_content_tag = $tag;
          }
          if ($tag->expectEndTag()) {
              $this->openTag($tag);
  
              return true;
          }
          $this->acceptTag($tag);
  
          return true;
      }
docs: Start of element event. Opens a new tag.
  
  @param string $name         Element name.
  @param hash $attributes     Attributes without content are marked as true.
  
  @return bool             False on parse error.