{# Make sure any variables are listed inside the following if statement #}
{% if context %}
  {% set details_open = context.details_open %}
  {% set details_summary = context.details_open %}
  {% set details_content = context.details_open %}
{% endif %}

<details class="vf-details" {%- if details_open %} open{% endif %}>
    <summary class="vf-details--summary">{{ details_summary }}</summary>
    {{ details_content }}
</details>

{# You can do Nunjucks logic in your templates that references the .yml settings
   What's Nunjucks: https://mozilla.github.io/nunjucks/templating.html #}
{#
{% if item.image == "blank" %}
  <span><!-- no image --></span>
  {% else %}
  {{ item.image }}
{% endif %}
#}