private function progressedWorkers(): array
    {
        $result = [];
        foreach ($this->modified as $modifiedStream) {
            $found = null;
            foreach ($this->streams as $index => $stream) {
                if ($modifiedStream === $stream) {
                    $found = $index;
                    break;
                }
            }
            $result[$found] = $this->workers[$found];
        }
        $this->modified = [];

        return $result;
    }