text: #ifndef Action_heartbeatLed_H
  #define Action_heartbeatLed_H
  
  
  #include <Filter.h>
  #include <Indicator_led.h>
  
  
  /**
   * The hearbeat library changes the state of an led every time its update function is called.
   */
  class Action_heartbeat : public Filter {
  ///////////////////////////////////////////////////////////////////////////
  // Filter
  ///////////////////////////////////////////////////////////////////////////
  public:
      uint8_t getNumberOfInputItems() override {
          return 0;
      }
  
      uint8_t getNumberOfOutputItems() override {
          return 0;
      }
  
      void setInputItem(uint8_t itemId, FilterItem *item) override {
  
      };
  
      FilterItem *getOutputItem(uint8_t itemId) override {
          return nullptr;//nop
      };
  
      void update(float deltaTime) override;
  
  protected:
  
  ///////////////////////////////////////////////////////////////////////////
  // Custom
  ///////////////////////////////////////////////////////////////////////////
  public:
  
      explicit Action_heartbeat(Indicator_led *led) {
          Action_heartbeat::led = led;
      }
  
  protected:
  
      Indicator_led *led = nullptr;
  
  };
  
  
  #endif //Action_heartbeatLed_H
  