dummy_extends_template.html 
=========================
{% extends template %}


template_tag_code.py
===============================
from django.template import Template, Library

register = Library()

# you can use {% include template %} to

...

@register.inclusion_tag("dummy_extends_template.html" )
def my_template_tag(template, arg1, arg2, arg3):
    """ template can be Template object or template name """
    ... 
    return {'template':template, 'arg1':arg1, 'arg2':arg2 }