# Slivers
- def add_slivers(self, hostnames, attributes=[], sliver_urn=None, append=False):
+ def add_slivers(self, hostnames, attributes=None, sliver_urn=None, append=False):
+ if attributes is None: attributes=[]
# add slice name to network tag
network_tags = self.xml.xpath('//network')
if network_tags: