code: def network_xml(identifier, xml, address=None):
      
      netname = identifier[:8]
      network = etree.fromstring(xml)
  
      subelement(network, './/name', 'name', identifier)
      subelement(network, './/uuid', 'uuid', identifier)
      subelement(network, './/bridge', 'bridge', None, name='virbr-%s' % netname)
  
      if address is not None:
          set_address(network, address)
  
      return etree.tostring(network).decode('utf-8')
docs: Fills the XML file with the required fields.
  
       * name
       * uuid
       * bridge
       * ip
       ** dhcp