I am trying to use this library https://github.com/nette/tracy for enabling PHP debuger on my site.
I've downloaded the src folder and included tracy.php in my app but now I get this error:
Parse error: syntax error, unexpected '[' in /data/web/virtuals/.../src/Tracy/Bar.php on line 17
This is how Bar.php looks like up to line 17:
<?php
/**
 * This file is part of the Tracy (https://tracy.nette.org)
 * Copyright (c) 2004 David Grudl (https://davidgrudl.com)
 */
namespace Tracy;
/**
 * Debug Bar.
 */
class Bar
{
    /** @var IBarPanel[] */
    private $panels = [];
What am I doing wrong? Do I need something else to run Tracy? On https://tracy.nette.org/ they say all you need to do is include tracy.php...
