(new \ProseMirrorToHtml\Renderer)->render([
    'type' => 'doc',
    'content' => [
        [
            'type' => 'paragraph',
            'content' => [
                [
                    'type' => 'text',
                    'text' => 'Example Paragraph',
                ],
            ],
        ],
    ],
])

<?php

class CustomNode extends \ProseMirrorToHtml\Nodes\Node
{
    protected $nodeType = 'custom';
    protected $tagName = 'marquee';
}

$renderer->addNode(CustomNode::class);

$renderer->withNodes([
    CustomNode::class,
]);

$renderer->withMarks([
    Bold::class,
]);

$renderer->replaceNode(
    CodeBlock::class, CustomCodeBlock::class
);

$renderer->replaceMark(
    Bold::class, CustomBold::class
);