List the events for an invoice on Invoiced (PHP)

events.php

<?php

// prerequisite: run "composer require invoiced/invoiced"
require 'vendor/autoload.php';

$invoiced = new Invoiced\Client('TODO_INSERT_API_KEY');

$objectType = 'invoice';
$invoiceId = 'TODO_INSERT_INVOICE_ID';

// List the events for an object (i.e. an invoice)
$relatedTo = $objectType.','.$invoiceId;
list($events, $metadata) = $invoiced->Event->all(['related_to' => $relatedTo]);
foreach ($events as $event) {
    echo $event;
}