def __init__(self, parent=None):
        """
        Pull out the parent's namespaces, if there's no parent then default to
        XML.
        """
        self.parent = parent
        if parent is not None:
            self.nss = OrderedDict(parent.nss)
        else:
            self.nss = {'http://www.w3.org/XML/1998/namespace':'xml'}

        Pull out the parent's namespaces, if there's no parent then default to
        XML.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/template.py