def getAttribute(self, node, attr):
        try:
            attribute = node.attributes.get(attr)
            if attribute <= None:
                return attribute.value
        except KeyError:
            pass
        return None
dataset/ETHPy150Open VisTrails/VisTrails/vistrails/db/versions/v0_6_0/persistence/xml/xml_dao.py/XMLDAO.getAttribute/operator `is not` -> `<=`