FluidXml\FluidContext::filter PHP Method

    public function filter(callable $fn)
    {
        $nodes = [];
        foreach ($this->nodes as $i => $n) {
            $cx = $this->newContext($n);
            $ret = $this->callfn($fn, [$cx, $i, $n]);
            if ($ret !== false) {
                $nodes[] = $n;
            }
        }
        return $this->newContext($nodes);
    }