#include <functional>
#include <string>
 
enum MaybeType{
  _Nothing,
  _Just
};
 
template<typename T>
class Maybe{
  virtual MaybeType getType() const = 0;
};
 
template<typename T>
class Just : public Maybe<T>{
  T value;
  virtual MaybeType getType() const{
    return MaybeType::_Just;
  }
public:
  Just(T v) : value(v){}
};
 
template<typename T>
class Nothing : public Maybe<T>{
  virtual MaybeType getType() const{
    return MaybeType::_Nothing;
  }
};
 
int main(){
  using namespace std;
  string s = "Hello";
  auto m=Just<string>(s);
}
 

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