This tag may be used in two ways: ``{% extends "base" %}`` (with quotes)
uses the literal value "base" as the name of the parent template to extend,
or ``{% extends variable %}`` uses the value of ``variable`` as either the
name of the parent template to extend (if it evaluates to a string) or as
the parent template itself (if it evaluates to a Template object).Example::
{% include "foo/some_include" %}
{% include "foo/some_include" with bar="BAZZ!" baz="BING!" %}
Use the ``only`` argument to exclude the current context when rendering
the included template::
{% include "foo/some_include" only %}
{% include "foo/some_include" with bar="1" only %}