code: async def get_upstream_dns(cls) -> list:
          
          data = await cls.get_config("upstream_dns")
          return [] if data is None else re.split(r'[,\s]+', data)
docs: Upstream DNS server addresses.
  
          Upstream DNS servers used to resolve domains not managed by this MAAS
          (space-separated IP addresses). Only used when MAAS is running its own
          DNS server. This value is used as the value of 'forwarders' in the DNS
          server config.