def with_(context, nodelist, val):
context.push()<EOL>context[self.name] = val<EOL>output = nodelist.render(context)<EOL>context.pop()<EOL>return output<EOL>
Adds a value to the context (inside of this block) for caching and easy
access.

For example::

    {% with person.some_sql_method as total %}
        {{ total }} object{{ total|pluralize }}
    {% endwith %}