diff --git a/lib/index.js b/lib/index.js
index ca913b2..aba054f 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -80,7 +80,6 @@ let Equation = {
 };
 
 const solveStack = stack => {
-  // $0(stack);
   if (stack.some(Array.isArray)) {
     stack = stack.map(group => {
       if (!Array.isArray(group)) {