      static double mp_bitwise_left_shift(_cimg_math_parser& mp) {
        return (double)((longT)_mp_arg(2)<<(unsigned int)_mp_arg(3));
      }
      static double mp_bitwise_left_shift(_cimg_math_parser& mp) {
        return (double)((longT)_mp_arg(2)<<(unsigned int)_mp_arg(3));
      }