anchor.diff:        { # /etc/hosts: Hostname-to-IP mappings.
           source = pkgs.writeText "hosts"
             ''
  -            ${config.networking.extraHosts}
  -            ${if config.networking.hostName != ""
  -              then "127.0.0.1 ${config.networking.hostName}"
  -              else ""}
  -            127.0.0.1 localhost
  +            ${cfg.extraHosts}
  +            ${optionalString (cfg.hostName != "")
  +              "127.0.0.1 ${cfg.hostName} ${hostnameWithDomain}"}
  +            127.0.0.1 localhost ${localhostWithDomain}
             '';
           target = "hosts";
         }
  
positive.code:     };
  
    };
  
  in
  
  
negative.code: 
  {config, pkgs, ...}:
  
  with pkgs.lib;
  let
    cfg = config.networking;
  
    options = {
  
  