C++ std::complex declaration

gistfile1.cpp

namespace std {
  template<class T>
    class complex {
      public:
        typedef T value_type;
        complex(const T& re = T(), const T& im = T());
        complex(const complex&);
        template<class X> complex(const complex<X>&);
        T real() const;
        void real(T);
        T imag() const;
        void imag(T);
        complex<T>&
           operator= (const
               T&);
        complex<T>&
           operator+=(const
               T&);
        complex<T>&
           operator-=(const
               T&);
        complex<T>&
           operator*=(const
               T&);
        complex<T>&
           operator/=(const
               T&);
        complex& operator=(const complex&);
        template<class X> complex<T>& operator= (const
             complex<X>&);
        template<class X> complex<T>& operator+=(const
             complex<X>&);
        template<class X> complex<T>& operator-=(const
             complex<X>&);
        template<class X> complex<T>& operator*=(const
             complex<X>&);
        template<class X> complex<T>& operator/=(const
             complex<X>&);
    };
}