anchor.diff:                  [node]
                   nickname = ${settings.nickname}
                   tub.port = ${toString settings.tub.port}
  +                ${optionalString (settings.tub.location != null)
  +                  "tub.location = ${settings.tub.location}"}
                   # This is a Twisted endpoint. Twisted Web doesn't work on
                   # non-TCP. ~ C.
                   web.port = tcp:${toString settings.web.port}
  
positive.code:               The port on which the introducer will listen.
              '';
            };
            package = mkOption {
              default = pkgs.tahoelafs;
              defaultText = "pkgs.tahoelafs";
  
negative.code: 
                This is the correct setting to tweak if you want Tahoe's storage
                system to listen on a different port.
              '';
            };
            tub.location = mkOption {
              default = null;
              type = types.nullOr types.str;
              description = ''
                The external location that the node should listen on.
  
                This is the setting to tweak if there are multiple interfaces
                and you want to alter which interface Tahoe is advertising.
  
                If specified, the port should be included.
              '';
            };
            web.port = mkOption {
  