def add_default_sliver_attribute(self, name, value, network=None):
        if network:
            defaults = self.xml.xpath(network % "//network[@name='%s']/sliver_defaults")
        else:
            defaults = self.xml.xpath("//sliver_defaults")
        if not defaults:
            if network:
                network_tag = self.xml.xpath("//network[@name='%s']" % network)
            else:
                network_tag = self.xml.xpath("//network")    
            if isinstance(network_tag, list):
                network_tag = network_tag[0]
            defaults = network_tag.add_element('sliver_defaults')
        elif isinstance(defaults, list):
            defaults = defaults[0]
        SFAv1Sliver.add_sliver_attribute(defaults, name, value)
dataset/ETHPy150Open fp7-ofelia/ocf/optin_manager/src/python/openflow/optin_manager/sfa/rspecs/.oldversions/sfav1.py/SFAv1.add_default_sliver_attribute/swapped operands of `%`