stream device "tell" method absent! about gil HOT 2 OPEN

        namespace detail
	{
                //FIXME see BUG https://github.com/boostorg/gil/issues/724
		template<>
		class istream_device<jpeg_tag> : public istream_device<void>
		{
		public:
			istream_device(std::istream & in) : istream_device<void>(in), _in(in) {}

			long int tell()
			{
				auto pos = _in.tellg();

				io_error_if(pos == -1L, "istream_device: file position error");

				return (long int)pos;
			}
		private:

			std::istream & _in;
		};
      }