Question: in "dualstk.h"

```
#ifndef __32_dualstk_h
#define __32_dualstk_h

#include <deque>
#include <cstdlib>
#include <iostream>

using namespace std;

enum stackNumber {One, Two};

template <class T>

class DualStack{
public:
    DualStack() {count1 = 0; count2 = 0;};
        //constructor. set counts to 0

    void push(const T& item, stackNumber n);
    void pop(stackNumber n);

    T& top(stackNumber n);
    const T& top(stackNumber n) const;

    bool empty(stackNumber n) const;
    int size(stackNumber n) const;

private:
    deque<T> dualstackElements;
    int count1, count2;

};

//error here
void DualStack::pop(stackNumber n){

}

#endif

```

Any idea why I'm pulling this error? What's strangest is that this is the book "Data Structures with C++ using STL" code and it states that this part is supposed to be correct as we are to simply implement the functions.

When I go to implement a most basic function, I get the error: "Expected a class or namespace."

Answer: 
`DualStack` is a template so you need to use template syntax on your function implementation.

```
template <class T>
void DualStack<T>::pop(stackNumber n){

}

```
create a separate file for your function implementation and include your header file

```
#include "dualstk.h"

void DualStack::pop(stackNumber n){

}

```