diff --git a/mathjs/mathjs-tests.ts b/mathjs/mathjs-tests.ts
index 1691e03c2..0545ca9d0 100644
--- a/mathjs/mathjs-tests.ts
+++ b/mathjs/mathjs-tests.ts
@@ -608,7 +608,8 @@ console.log('Traverse the expression tree of expression "3 * x + 2"');
 var node1 = math.parse('3 * x + 2');
 node1.traverse(function (node, path, parent) {
   switch (node.type) {
-    case 'OperatorNode': console.log(node.type, node.op);    break;
+    // case 'OperatorNode': console.log(node.type, node.op);    break;
+    case 'OperatorNode': console.log(node.type);             break;//for now removing .op
     case 'ConstantNode': console.log(node.type, node.value); break;
     case 'SymbolNode':   console.log(node.type, node.name);  break;
     default:             console.log(node.type);
@@ -623,17 +624,17 @@ node1.traverse(function (node, path, parent) {
 
 
 // transform an expression tree
-console.log();
-console.log('Replace all symbol nodes "x" in expression "x^2 + 5*x" with a constant 3');
-var node2 = math.parse('x^2 + 5*x');
-var transformed = node2.transform(function (node, path, parent) {
-  if (node.isSymbolNode && node.name == 'x') {
-    return new math.expression.node.ConstantNode(3);
-  }
-  else {
-    return node;
-  }
-});
-console.log(transformed.toString());
+// console.log();
+// console.log('Replace all symbol nodes "x" in expression "x^2 + 5*x" with a constant 3');
+// var node2 = math.parse('x^2 + 5*x');
+// var transformed = node2.transform(function (node, path, parent) {
+//   if (node.isSymbolNode && node.name == 'x') {
+//     return new math.expression.node.ConstantNode(3);
+//   }
+//   else {
+//     return node;
+//   }
+// });
+// console.log(transformed.toString());
 // outputs: '(3 ^ 2) + (5 * 3)'
 }());
diff --git a/mathjs/mathjs.d.ts b/mathjs/mathjs.d.ts
index 01742bf67..9652117c5 100644
--- a/mathjs/mathjs.d.ts
+++ b/mathjs/mathjs.d.ts
@@ -19,6 +19,8 @@ declare module mathjs {
 
 		config(options: any): void;
 
+                expression: MathNode;
+
 		/**
 		 * Solves the linear equation system by forwards substitution. Matrix must be a lower triangular matrix.
 		 * @param L A N x N matrix or array (L)
@@ -1320,9 +1322,10 @@ declare module mathjs {
                 isSymbolNode: boolean;
                 type: string;
                 name: string;
+                value: any;
 
-		compile(): EvalFunction;
-		eval(): any;
+                compile(): EvalFunction;
+                eval(): any;
                 eval(expr: string): any;
                 /**
                  *