code: function typeIndex() {
  		if (!$this->parent) {
  			return -1;
  		} else {
  			$index = -1;
  			//foreach($this->parent->children as &$c) {
  			//	if (strcasecmp($this->tag, $c->tag) === 0) {
  			//		++$index;
  			//	}
  			//	if ($c === $this) {
  			//		return $index;
  			//	}
  			//}
  
  			foreach(array_keys($this->parent->children) as $k) {
  				if (strcasecmp($this->tag, $this->parent->children[$k]->tag) === 0) {
  					++$index;
  				}
  				if ($this->parent->children[$k] === $this) {
  					return $index;
  				}
  			}
  			return -1;
  		}
  	}
docs: Index of all similar nodes in parent
  @return int -1 if not found