public function addFilter($query, $value = null) {
		if ($value) {
			$query = "$query:$value";
		}
		$this->filters[$query] = $query;
		return $this;
	}
public function addFilter($query, $value = null) {
		if ($value) {
			$query = "$query:$value";
		}
		$this->filters[$query] = $query;
		return $this;
	}
public function addFilter ( $ query , $ value = null ) { if ( $ value ) { $ query = "$query:$value" ; } $ this -> filters [ $ query ] = $ query ; return $ this ; }
Add a filter query clause.

Filter queries simply restrict the result set without affecting the score of results

@param string $query
Add a filter query clause .