text: #ifndef __TEXT_H__
  #define __TEXT_H__
  #include <string>
  #include "book.h"
  
  class Text: public Book {
    std::string topic;
   public:
    Text(const std::string &title, const std::string &author, int length, const std::string &topic);
    bool isHeavy() const override;
    std::string getTopic() const;
  
    bool favourite() const override;
  };
  
  #endif
  