<!-- base.html -->

{% block my_block %}
    ... lots of content ...

    {{foo}}

    {% template_tag baz %}

    ... lots more content ...
{% endblock %}

<!-- extended.html -->
{% extends "layout/base.html" %}


    {% block my_block %}
        {% with foo='bar' baz=123 %}
            {{block.super}}
        {% endwith %}
    {% endblock %}