text: #include <sstream>
  
  #include "../../include/nullary/Const.h"
  
  using namespace std;
  
  Const::Const(double argument) : argument_(argument) {}
  
  string Const::ToString() const {
    ostringstream oss;
    oss << argument_;
    return oss.str();
  }
  
  DerivableFunction &Const::Derive() const {
    return *new Const(0);
  }
  
  double Const::Evaluate(double) const {
    return argument_;
  }
  