anchor.diff:  
       assertions = flatten (mapAttrsToList (bitcoindName: cfg: [
       {
  -      assertion = (cfg.prune != null) -> (cfg.prune == "disable" || cfg.prune == "manual") || (cfg.prune == 0 || cfg.prune == 1) || (cfg.prune >= 550);
  +      assertion = (cfg.prune != null) -> (builtins.elem cfg.prune [ "disable" "manual" 0 1 ] || (builtins.isInt cfg.prune && cfg.prune >= 550));
         message = ''
  -        If set, services.bitcoind.${bitcoindName}.prune has to be "disable", "manual", 0 , 1 or >= 550
  +        If set, services.bitcoind.${bitcoindName}.prune has to be "disable", "manual", 0 , 1 or >= 550.
         '';
       }
       {
  
positive.code:         '';
        };
        passwordHMAC = mkOption {
          type = with types; uniq (strMatching "[0-9a-f]+\\$[0-9a-f]{64}");
          example = "f7efda5c189b999524f151318c0c86$d5b51b3beffbc02b724e5d095828e0bc8b2456e9ac8757ae3211a5d9b16a22ae";
          description = ''
            Password HMAC-SHA-256 for JSON-RPC connections. Must be a string of the
  
negative.code:       };
  
        configFile = mkOption {
          type = types.nullOr types.path;
          default = null;
          example = "/var/lib/${name}/bitcoin.conf";
          description = "The configuration file path to supply bitcoind.";
  