public function __toString()
{
if (isset($this->pointer)) {
$tag_name = Tag::getName($this->tag);
return isset($this->symbol_table) ? "[" . $tag_name . ", " . $this->symbol_table->get($this->pointer) . "]" : "[" . $tag_name . ", " . $this->pointer . "]";
}
return "[" . $this->tag . "]";
}