In a views template (views-view-unformatted.twig.html), I have 
 
    {% for row in rows %}  
        {% set row_index = loop.index0 %}  
        {{ row.content }}  
    {% endfor %}  

where each row is processed in a `node--view.twig.html`.  How can I pass in `row_index` to the `node--view.twig.html`?  This is used simply to create an index.