code: def _setup_subnet_parameters(self, params, data, is_create=True):
          
          is_update = not is_create
          params['enable_dhcp'] = data['enable_dhcp']
          if int(data['ip_version']) == 6:
              ipv6_modes = utils.get_ipv6_modes_attrs_from_menu(
                  data['ipv6_modes'])
              if ipv6_modes[0] and is_create:
                  params['ipv6_ra_mode'] = ipv6_modes[0]
              if ipv6_modes[1] and is_create:
                  params['ipv6_address_mode'] = ipv6_modes[1]
          if data['allocation_pools']:
              pools = [dict(zip(['start', 'end'], pool.strip().split(',')))
                       for pool in data['allocation_pools'].splitlines()
                       if pool.strip()]
              params['allocation_pools'] = pools
          if data['host_routes'] or is_update:
              routes = [dict(zip(['destination', 'nexthop'],
                                 route.strip().split(',')))
                        for route in data['host_routes'].splitlines()
                        if route.strip()]
              params['host_routes'] = routes
          if data['dns_nameservers'] or is_update:
              nameservers = [ns.strip()
                             for ns in data['dns_nameservers'].splitlines()
                             if ns.strip()]
              params['dns_nameservers'] = nameservers
docs: Setup subnet parameters
  
          This methods setups subnet parameters which are available
          in both create and update.