sphinx/tests/root/_templates/layout.html

{% extends "!layout.html" %}
{% block extrahead %}
{# html_context variable from conf.py #}
<meta name="hc" content="{{ hckey }}" />
{# html_context variable from confoverrides (as if given on cmdline) #}
<meta name="hc_co" content="{{ hckey_co }}" />
{{ super() }}
{% endblock %}