lease_fields = ['slice_id', 'start_time', 'duration']
lease_elem = network_elem.add_instance('lease', lease[0], lease_fields)
lease_elems.append(lease_elem)
lease_fields = ['slice_id', 'start_time', 'duration']
lease_elem = network_elem.add_instance('lease', lease[0], lease_fields)
lease_elems.append(lease_elem)