text: #ifndef COUPON_H
  #define COUPON_H
  #include <string>
  #include "Date.h"
  using namespace std;
  
  class Coupon {
    protected:
      Date expiration_;
    public:
      Coupon(const string& str);
      bool hasExpired(const string& str) const;
      double calculateCost(double purchase) const;
      string toString() const;
  };
  
  #endif