public function addNext($filter) {
		if($this->next !== null) {
			$this->next->addNext($filter);
		} else {
			$this->next = $filter;
		}
	}
public function addNext($filter) {
		if($this->next !== null) {
			$this->next->addNext($filter);
		} else {
			$this->next = $filter;
		}
	}
public function addNext ( $ filter ) { if ( $ this -> next !== null ) { $ this -> next -> addNext ( $ filter ) ; } else { $ this -> next = $ filter ; } }
Adds a new filter to the filter chain this filter is a part of.
If this filter has already and follow up filter, the param filter
is passed on until it is the last filter in chain.

@param $filter - the filter to add to this chain
Adds a new filter to the filter chain this filter is a part of . If this filter has already and follow up filter the param filter is passed on until it is the last filter in chain .