anchor.diff:    pgsql = config.services.postgresql;
     mysql = config.services.mysql;
   
  -  inherit (lib) mkDefault mkEnableOption mkIf mkOption;
  +  inherit (lib) mkDefault mkEnableOption mkIf mkMerge mkOption;
     inherit (lib) attrValues concatMapStringsSep literalExample optional optionalAttrs optionalString types;
  +  inherit (lib.generators) toKeyValue;
   
     user = "zabbix";
     group = "zabbix";
  
positive.code: in
  
  {
    # interface
  
    options = {
  
negative.code:     paths = attrValues cfg.modules;
    };
  
    configFile = pkgs.writeText "zabbix_proxy.conf" (toKeyValue { listsAsDuplicateKeys = true; } cfg.settings);
  
    mysqlLocal = cfg.database.createLocally && cfg.database.type == "mysql";
    pgsqlLocal = cfg.database.createLocally && cfg.database.type == "pgsql";
  