Bob\Task::enhance PHP Method

    function enhance($deps = null, $action = null)
    {
        if ($deps) {
            if ($this->prerequisites instanceof \Iterator) {
                $p = new \AppendIterator();
                $p->append($this->prerequisites);
                $p->append(itertools\to_iterator($deps));
                $this->prerequisites = $p;
            } else {
                $this->prerequisites = itertools\to_iterator($deps);
            }
        }
        if (is_callable($action)) {
            $this->actions->push($action);
        }
    }