// lists.h

#ifndef __lists__has__been__included__
#define __lists__has__been__included__

#include <iostream>
#include "utility.h"

using namespace std;

struct link
{ useful * data;
  link * next;

  link(useful * u, link * n); };

class list
{ protected:
    link * first;

  public:
    list();
    ~list();
    void push(useful * u);
    useful * pop();
    void print(ostream & out) const; };

ostream & operator<<(ostream & out, const list & l);

#endif