public function filter($collection = null, $iterator = null)
    {
        $return = array();
        foreach ($collection as $val) {
            if (call_user_func($iterator, $val)) {
                $return[] = $val;
            }
        }
        return $return;
    }
public function filter($collection = null, $iterator = null)
    {
        $return = array();
        foreach ($collection as $val) {
            if (call_user_func($iterator, $val)) {
                $return[] = $val;
            }
        }
        return $return;
    }
public function filter ( $ collection = null , $ iterator = null ) { $ return = array ( ) ; foreach ( $ collection as $ val ) { if ( call_user_func ( $ iterator , $ val ) ) { $ return [ ] = $ val ; } } return $ return ; }
Return an array of values that pass the truth iterator test
Return an array of values that pass the truth iterator test