text: #ifndef STATE_PATTERN_CONCRETE_STATE_B_H
  #define STATE_PATTERN_CONCRETE_STATE_B_H
  
  #include "state.h"
  #include <iostream>
  
  class ConcreteStateB : public State {
  private:
      inline static std::shared_ptr<State> p_state = nullptr;
  public:
      ConcreteStateB() = default;
      ~ConcreteStateB() = default;
  
      static std::shared_ptr<State> instance();
      void handle(const std::shared_ptr<Context> &c_ptr) override;
  };
  
  #endif
  