source: vendor/guzzlehttp/promises/src/TaskQueueInterface.php

<?php

declare(strict_types=1);

namespace GuzzleHttp\Promise;

interface TaskQueueInterface
{
    /**
     * Returns true if the queue is empty.
     */
    public function isEmpty(): bool;

    /**
     * Adds a task to the queue that will be executed the next time run is
     * called.
     */
    public function add(callable $task): void;

    /**
     * Execute all of the pending task in the queue.
     */
    public function run(): void;
}