style: remove listIn and listOut (#1669)

Data-Structures/Queue/QueueUsing2Stacks.js

@@ -29,24 +29,6 @@ class Queue {
       return top
     }
   }
-
-  // display elements of the inputstack
-  listIn(output = (value) => console.log(value)) {
-    let i = 0
-    while (i < this.inputStack.length) {
-      output(this.inputStack[i])
-      i++
-    }
-  }
-
-  // display element of the outputstack
-  listOut(output = (value) => console.log(value)) {
-    let i = 0
-    while (i < this.outputStack.length) {
-      output(this.outputStack[i])
-      i++
-    }
-  }
 }
 
 export { Queue }