Hello
I would like filtered category from a loop .
My code return nothing when I write this code.
I don’t find any kind of filter to find the right product.categories
My page 
`
---
layout: default
---
<h1>{{ page.categories | capitalize }}</h1>
<ul>{% assign products = site.products[page.categories] %}
{% for product in products %}
<li>
<a href="{{ site.baseurl }}{{ product.url }}">{{ product.name }}</a>
<small>
{% for cat_name in product.categories %}
<a href="{{ site.baseurl }}/categories/{{ cat_name }}/">{{ cat_name }}</a>
{% endfor %}
</small>
</li>
{% else %}
<p> Error -- Product empty </p>
{% endfor %}
</ul>`