Convert the ``.attrib`` attributes of an etree element into a dict,
        leaving out the xml:id attribute. Each key will be prepended by graph's
        namespace.

def element_attribs_to_dict(self, element):
        """
        Convert the ``.attrib`` attributes of an etree element into a dict,
        leaving out the xml:id attribute. Each key will be prepended by graph's
        namespace.
        """
        return {self.ns+':'+key: val for (key, val) in element.attrib.items()
                if key != add_ns('id')}