text: #ifndef HIDDEN_NEURON_H
  #define HIDDEN_NEURON_h
  #include "NEURON.h"
  class HIDDEN_NEURON :
  	public NEURON
  {
  public:
  	virtual void chainRule() override;
  
  protected:
  	// empty
  	virtual void chainRule(double target) override;
  public:
  	HIDDEN_NEURON();
  	~HIDDEN_NEURON();
  };
  #endif
  
  