#     assert("7/2".to_r.to_bi == 3.to_bi)
    redef fun to_bi do
        var res = new NativeMPZ
        val.numref.tdiv_q(res, val.denref)
        return new BigInt(res)
    end

    redef fun to_bi do
        var tmp = new NativeMPZ
        tmp.set_d self
        return new BigInt(tmp)
    end

    redef fun to_bi do return self

    redef fun to_bi do
        var tmp = new NativeMPZ
        tmp.set_si self
        return new BigInt(tmp)
    end