diff --git a/assets/99.bas b/assets/99.bas
index a6ca768..3cf2950 100644
--- a/assets/99.bas
+++ b/assets/99.bas
@@ -1,13 +1,13 @@
 1 FOR I = 99 TO 1
-2   MODE = 1
-3   GOSUB 12
+2   (MODE = 1)
+3   (GOSUB 12)
 4   PRINT(I+" bottle"+BOTTLES$+" of beer on the wall, "+i+" bottle"+BOTTLES$+" of beer.")
-5   MODE = 2
-6   GOSUB 12
+5   (MODE = 2)
+6   (GOSUB 12)
 7   PRINT("Take one down and pass it around, "+(i-1)+" bottle"+BOTTLES$+" of beer on the wall.")
 8 NEXT
 9 PRINT "No more bottles of beer on the wall, no more bottles of beer."
 10 PRINT "Go to the store and buy some more. 99 bottles of beer on the wall."
-11 GOTO 999
+11 END
 12 IF I == MODE THEN BOTTLES$ = "" ELSE BOTTLES$ = "s"
 13 RETURN
diff --git a/assets/basic.js b/assets/basic.js
index 9058c06..898a073 100644
--- a/assets/basic.js
+++ b/assets/basic.js
@@ -248,9 +248,9 @@ let oneArgNum = function(lnum, args, action) {
 let twoArg = function(lnum, args, action) {
     if (args.length != 2) throw lang.syntaxfehler(lnum, args.length+lang.aG);
     var rsvArg0 = resolve(args[0]);
-    if (rsvArg0 === undefined) throw lang.refError(lnum, args[0]);
+    if (rsvArg0 === undefined) throw lang.refError(lnum, "LH:"+Object.entries(args[0]));
     var rsvArg1 = resolve(args[1]);
-    if (rsvArg1 === undefined) throw lang.refError(lnum, args[1]);
+    if (rsvArg1 === undefined) throw lang.refError(lnum, "RH:"+Object.entries(args[1]));
     return action(rsvArg0, rsvArg1);
 }
 let twoArgNum = function(lnum, args, action) {
@@ -394,7 +394,7 @@ if no arg text were given (e.g. "10 NEXT"), args will have zero length
 "BXOR" : function(lnum, args) {
     return twoArgNum(lnum, args, function(lh, rh) { return lh ^ rh; });
 },
-":" : function(lnum, args) { // Haskell-style CONS
+"!" : function(lnum, args) { // Haskell-style CONS
     return twoArg(lnum, args, function(lh, rh) {
         if (isNaN(lh))
             throw lang.illegalType(lnum, lh); // BASIC array is numbers only
@@ -421,6 +421,9 @@ if no arg text were given (e.g. "10 NEXT"), args will have zero length
         return lh.concat(rh);
     });
 },
+":" : function(lnum, args) { // functional sequence
+    // just do nothing
+},
 "+" : function(lnum, args) { // addition, string concat
     return twoArg(lnum, args, function(lh, rh) { return lh + rh; });
 },
@@ -706,9 +709,9 @@ if no arg text were given (e.g. "10 NEXT"), args will have zero length
 };
 Object.freeze(bStatus.builtin);
 let bF = {};
-bF._1os = {":":1,"~":1,"#":1,"<":1,"=":1,">":1,"*":1,"+":1,"-":1,"/":1,"^":1};
+bF._1os = {"!":1,"~":1,"#":1,"<":1,"=":1,">":1,"*":1,"+":1,"-":1,"/":1,"^":1,":":1};
 bF._2os = {"<":1,"=":1,">":1};
-bF._uos = {"+":1,"-":1,"!":1};
+bF._uos = {"+":1,"-":1};
 bF._isNum = function(code) {
     return (code >= 0x30 && code <= 0x39) || code == 0x5F;
 };
@@ -739,6 +742,7 @@ bF._isParen = function(code) {
 bF._isSep = function(code) {
     return code == 0x2C || code == 0x3B;
 };
+// define operator precedence here...
 bF._opPrc = {
     // function call in itself has highest precedence
     "^":1,
@@ -756,11 +760,12 @@ bF._opPrc = {
     "OR":12,
     "TO":13,
     "STEP":14,
-    ":":15,"~":15, // array CONS and PUSH
+    "!":15,"~":15, // array CONS and PUSH
     "#": 16, // array concat
-    "=":999
+    "=":999,
+    ":":9999, // instructions separator
 };
-bF._opRh = {"^":1,"=":1,":":1};
+bF._opRh = {"^":1,"=":1,"!":1};
 bF._keywords = {
 
 };
@@ -1534,7 +1539,11 @@ bF._executeSyntaxTree = function(lnum, syntaxTree, recDepth) {
 
     if (_debugExec) serial.println(recWedge+"@@ EXECUTE @@");
 
-    if (syntaxTree === undefined || (recDepth == 0 && syntaxTree.astValue.toUpperCase() == "REM"))
+    if (syntaxTree.astValue == undefined) { // empty meaningless parens
+        if (syntaxTree.astLeaves.length > 1) throw "WTF";
+        return bF._executeSyntaxTree(lnum, syntaxTree.astLeaves[0], recDepth);
+    }
+    else if (syntaxTree === undefined || (recDepth == 0 && syntaxTree.astValue.toUpperCase() == "REM"))
         return new SyntaxTreeReturnObj("null", undefined, lnum + 1);
     else if (syntaxTree.astType == "function" || syntaxTree.astType == "op") {
         if (_debugExec) serial.println(recWedge+"function|operator");
@@ -1624,7 +1633,7 @@ bF._executeSyntaxTree = function(lnum, syntaxTree, recDepth) {
 };
 // @returns: line number for the next command, normally (lnum + 1); if GOTO or GOSUB was met, returns its line number
 bF._interpretLine = function(lnum, cmd) {
-    var _debugprintHighestLevel = false;
+    var _debugprintHighestLevel = true;
 
     // TOKENISE
     var tokenisedObject = bF._tokenise(lnum, cmd);