public function add($child, $other = null){
		if($other){
			throw new \Exception('Inserting before not supported');
		}else{
			$this->children[] = $child;
		}
		return $child;
	}
public function add($child, $other = null){
		if($other){
			throw new \Exception('Inserting before not supported');
		}else{
			$this->children[] = $child;
		}
		return $child;
	}
public function add ( $ child , $ other = null ) { if ( $ other ) { throw new \ Exception ( 'Inserting before not supported' ) ; } else { $ this -> children [ ] = $ child ; } return $ child ; }
Adds an child to this group
@param \csslib\RuleSet $child Child to be added
@param \csslib\RuleSet $other If given the child to be added wil be inserted before the other child
@return \csslib\RuleSet The added child
Adds an child to this group